Why Density Requires Height

Among modern urbanists, the universal consensus that the postwar urban form of towers in parks is bad gives way to fractious disagreements about which urban form to replace them with. The main battle lines are drawn between libertarians and such liberal sympathizers as Matt Yglesias who argue for removing zoning laws and building tall buildings on the model of Manhattan, and social liberals in the tradition of Christopher Alexander who argue for height limits and traditional pre-19th century urbanism. On the blogosphere, the most consistent advocate of the former is Market Urbanism, and the most consistent advocate of the latter is Old Urbanist.

The primary argument used by height limit proponents is aesthetic. Charlie of Old Urbanist quotes the following passage from Nathan Glazer’s book, From a Cause to a Style:

Wherever social scientists examine these issues, they find a taste that architects on the whole do not find it interesting to satisfy, a taste for the low-rise, the small scale, the unit that gives some privacy, some access to the ground, a small piece of land wholly under one’s control.  I am not, of course, describing a universal taste,  But for people raising children – and indeed many others – it is a near universal taste, if people have a choice.  Nor is there any reason to think that is is necessary or desirable that people be educated against that taste and develop a taste for a larger or gargantuan scale…

A good rule of thumb is that one should dismiss every claim of a “near universal taste” that is not universal in the literal sense – and this one is not. I’m basing my impression on Charlie’s post and it could be that Glazer provides more justification for the universality of the desire for single-family owner-occupied housing, but outside the US, I just don’t see it. It’s not present in Tel Aviv, Paris, or any other city where the rich usually live in multi-story buildings, on their own volition. In Paris one at least has the consolation that people live in mid-rise buildings; Tel Aviv, where those mid-rise buildings are for the upper middle class while the rich live in modernist skyscrapers, has no such excuse. Even Manhattan is undergoing an upper-class baby boom, so even in the US families with children are no longer shunning the city.

In general, it’s easy to dismiss everything one does not like as going against a universal taste. All one needs is to point to universal acceptance in places where government regulations mandate one’s preference (for example, suburbia in most of the US) and, if one wants to be more self-conscious, then harangue about government regulations elsewhere mandating the opposite. In reality, the rich live where other rich people live, in gated communities, which can have any urban form; the middle class lives where the rest of the middle class lives; the poor live where housing is cheap. Even modernist projects can do: for middle-class examples, consider New York’s Co-op City and Stuyvesant Town.

In contrast, the primary argument used by height limit opponents is utilitarian: density requires height. This is obvious in central business districts, where the economics of agglomeration favor very large buildings, and vertical CBDs such as Midtown and Lower Manhattan and the Chicago Loop can attain very high densities. The footprint of the Empire State Building has a floor area ratio of 33, that of the Sears Willis Tower 37. It’s impossible to get anywhere this density without multiple tens of floors, even with buildings that rise vertically from the lot limit without tapering.

Unfortunately, this point is easy to miss, since the headline figure of density is residents per unit of area, and residential skyscrapers are rare. Skyscraper-ridden Manhattan and height-limited Paris have about the same residential density, but Manhattan’s skyscrapers are predominantly commercial. Aside from project towers, Manhattan’s residential urban form is mid-rise, with most buildings not exceeding 6-12 floors; this is similar to Paris.

Indeed, the last time I visited Paris I instantly felt at home, as if in a French-speaking Manhattan. The architectural styles are similar. The building height in Paris is the same as what I’m used to from living in Upper Manhattan. The street widths are on average similar, though Manhattan’s street widths are more uniform whereas Paris has many 10-meter-wide streets as well as many 40-meter-wide boulevards. Both places are the densest major clusters one can find in the developed world outside Hong Kong; this is about the limit one can get with mid-rise buildings flanking moderately wide streets.

To get higher density, one must build higher. Some parts of Manhattan do: the Upper East Side and Upper West Side have a fair number of buildings in the 20-30 story range, and although as Charlie computes only 1% of New York City’s residents live above the 19th floor, the proportion is much higher on the Upper East Side and Upper West Side, and becomes even higher if one relaxes the limit from 20 floors to 12, already well beyond the limit traditional urbanists and high-rise opponents accept (Christopher Alexander proposes 5 as the limit). Those are precisely the neighborhoods with the highest density in Manhattan. The census tracts where the residents are upper middle-class rather than rich – generally those in the north or east of the Upper East Side – have residential densities of about 50,000-75,000 per square kilometer. In contrast, the average in Manhattan and Paris is about 25,000, and the densest quarter of Paris has about 40,000.

I’m unconvinced they’re clearly inferior to densely packed mid-rise buildings; zoning boards and NIMBYs can be just as shrill toward narrow streets, without which small buildings limit density to suburban levels, as they are toward high-rises. And when demand is so great that even 40,000 people per km^2 at modern urban apartment sizes is not enough – a demand that’s familiar for office towers, but relatively new for residences – higher buildings become a necessity. They do not have to have 50 floors as Ed Glaeser proposes, but any limit lower than 20 is an unreasonable constraint in this case.

I’m not going to make an aesthetic or environmental argument here. People of means have had no trouble living with very narrow streets in Tokyo, or with very wide avenues and high-rises. But, please, do not pretend you can limit height without limiting density. There’s a point beyond which demand will exceed your height limit.


  1. JJJ

    You should look into the way Brazilian cities are built. The majority of people live in highrise buildings (high in this case being 10-30 floors, because at least I consider mid rise to me 4-10). Take for example Curitiba (of BRT fame). The “skyline” is actually highrise buildings built along the BRT route.

    Thats all residential.

    You can see it on a grander scale here, with the commercial core (a square area) being high rises, and the residential buildings radiating from that along the BRT routes.

    Besides the BRT aspect, residential apartment living is the standard all over Brazil. So it’s somewhere between Paris and Manhattan.

    It also makes cities appear to be bigger. here’s Londrina, population around 500k.

    Note that these cities DO have height limits. These limits are actually based on things like fire safety. The government simply finds it too expensive to buy equipment that can handle fires on the 50th floor of a building, for example. Sewage is another one.

    From what Ive seen of China (never been), theyre following a similar model.

    Of course the claim that people with families want to be near the ground is ludicrous. People with families want to do what other people with families are doing (ie, raise their kids in the most normal, accepted fashion). If living in apartment 1502 is what’s normal, then there’s no hesitation in doing that.

    • Danny

      More like the standard in the coastal cities of Brazil. Even in super urban Sao Paulo, most residences are lowrise, and suburban single family homes are at a scale that Dallas could be jealous of.

      • JJJ

        Neither of those cities are anywhere near the coast. And Sao Paulo is packed with apartments, theyre just not in corridors.

  2. Danny

    The old urbanist style urbanism is nothing more than romanticism. People’s preferences and styles change, and that is the real universal fact. I love Beaux-Arts architecture, and from an urban perspective, it is unparalleled IMHO. But that doesn’t mean that its time is over and that building a Beaux Arts building today would be anything more than an imitation.

    That being said, eliminating zoning doesn’t automatically mean that highrises will replace all the lowrises. People’s preferences still dominate development decisions, and not everybody is going to want to live in highrises.

    In fact, I personally think that while the average residential tower size would increase, the super highrise would probably decrease. As is inherent in any zoning situation, politicization determines the exceptions. “You want to build a 40 story tower? No can do. But if you want to build a memorial to monumentalism, bring a few thousand jobs to downtown, break height records, bring the architecture magazine photographers in droves, and help me secure my incumbency as mayor, of course you can…hell, we might even subsidize you.”

    Zoning only works by restriction. And from a public choice perspective, the only things that get restricted are the things that don’t increase pay, prestige, or power. An ordinary 35 story residential tower or even commercial tower does not do that.

  3. Alex B.

    I do think Christopher Alexander’s 5 story definition is a good one – that’s more or less the boundary between an building that can function as a walk-up, vs. one that requires elevators for vertical circulation. From a development perspective, that also more or less demarcates the line between what’s possible with stick-built construction and heights that require ‘high rise’ building techniques of reinforced concrete and steel.

    Alon’s point about NIMBY resistance to any form of change (whether it be narrow streets or tall buildings) is a good one – but I’d also note that outside of areas like New York, the notion that greater density can indeed be achieved without skyscrapers is worth noting. Too often, NIMBY opposition to even modest upzoning of an area around a transit stop brings forward outlandish cries of ‘Manhattanization.’ Those claims are disingenuous and inaccurate, of course – but they can still be quite effective in making the argument through the various planning and zoning bodies and to the public as a whole. In many places, the middle way of greatly increased density without large increases in height is not only possible, but desirable.

    The NIMBYs will always have an advantage since it is easier to oppose than it is to propose, and easier to destroy than it is to create. That said, for many cases (particularly for suburban retrofits) being able to de-couple density from height can be useful.

    Another concern is economic – if people say they want 8 story buildings, that means you need the same construction techniques for 8 stories as you need for 20, and all the added costs that go with it – just without those extra 12 floors to get the return on investment.

    • EngineerScotty

      In many US jurisdictions, the cutoff is 3 stories, not 5–building codes, at least out here in Orygun, require elevators for any structure greater than 3 stories in height. Three stories is also a practical limit for wood-frame construction, and much higher than that also starts to require things like pumps to transport clean water to the upper levels.

      The three-story suburban apartment complex is a ubiquitous form in these parts.

      • Alex B.

        Well, at least here in DC you can get to 5 with the first floor in concrete and stick-built above that – then again, we don’t have the seismic threats that you likely do in PDX.

        And I do think that it would be wise for any new construction to include elevators, but my larger point was that an elevator is not a de facto requirement for the people living in that building, even if it is required by code.

        Nevertheless, regardless of where that break is, I do think that represents a good analytical breaking point – particularly if the goal of adding density is to help bring housing costs down and provide a relatively quick way to add density around transit.

      • Alon Levy

        In Tel Aviv, the cutoff is 4, because the older buildings are in a neighborhood whose zoning plan called for 4-story buildings. I’m pretty sure nothing in Tel Aviv is made of wood – those older buildings are made of brick. In New York, I’ve seen 6-story walkups.

        The tallest residential buildings I’ve heard of before the industrial era are 9-story, in the Middle East. I forget what city they were in – I think Sanaa. It was mentioned in a thread on The Overhead Wire several years ago. (Ancient Rome went up to 6 floors, if I remember correctly.)

      • Nathanael

        As a point of curiosity, the tallest pre-industrial “buildings” were probably the communities built into cliff walls, such as those in the sides of the Mesas in the Southwest. Climb up and down rope ladders to go between dwellings! Definitely a lot taller than 9 stories, but, well, not exactly a building.

    • Nathanael

      The fact is that the sheer number of mobility-impaired people in a richer, older society means that you want to have lots of residential buildings with elevators *anyway*.

      So designing to encourage walkups is not wise.

  4. Tom West

    The interesting question to is *why* people prefer to live in a buidling/piece of land wholly under their control, or alternatively, what the percieve as being bad a multiple-unit building. A few thoughts:
    1) Noise from neighbours
    2) Lack of control over communal areas
    3) Lack of control over what you can to your unit
    4) Having to rely on the building’s management for certain repairs etc.
    5) Having to pay some sort of monthyl fees, even if you “own” the unit
    The first is a construciton-quality issue, while (3) and (4) are a problems if the building is poorly managed. If you are rich, all these problems are much less liekly to exist, because you can afford to live in a better-construted building; you will get better service by paying more; and the fees will seem less important.

    This implies that high-rise buildings are better for richer people than for poor people.

    • EngineerScotty

      Some people object to things like shared laundry facilities–even though a good argument can be made that every household with their own washer and dryer (and space for these) is wasteful.

      Numbers 2, 3, and 5 also apply to many types of owner-occupied single-family housing where there is an HOA involved. Number 4 likewise applies to any sort of rental housing.

      • Tom West

        I’m not quite sure what your point is – but it seems to re-enforce the notion that fo most peopel, the most desirable state is to own your piece of land and a building thereon. (I would *never* buy a house with any sort of HOA).

      • EngineerScotty

        As far as “not really owning” one’s real estate goes–it’s interesting to compare two differing states of affairs:

        * Owning real estate which is part of an HOA
        * Owning real estate which is subject to municipal property taxes and regulations.

        Many consider the former to be more obnoxious than the latter. HOAs are infamous for petty and unprofessional conduct–with HOA officers using their powers to indulge in grievances against neighbors; we’ve all heard horror stories about people getting fined because their front lawns are a half-centimeter too high. Municipal governments are much less likely to engage in this sort of conduct (although some cities do have rather precise standards for property maintenance)–particularly in larger cities, where the scope of responsibility simply prevents officials grinding axes against their neighbors.

        OTOH, I’ve seen more than a few libertarians argue with a straight face that municipal government is hostile to liberty as it is “involuntary”, whereas HOAs and covenants and similar are voluntary contractual arrangements among homeowners, and thus perfectly legitimate–even though the vast majority of these are set up by builders/developers, as opposed to voluntarily organized by neighbors in an existing development.

  5. Charlie

    The footprint of the Empire State Building has a floor area ratio of 33, that of the Sears Willis Tower 37. It’s impossible to get anywhere this density without multiple tens of floors, even with buildings that rise vertically from the lot limit without tapering.

    Alon: I obviously can’t dispute the point that a traditional city is not going be able to provide a citywide FAR of 30+ (though I’m sure even midtown Manhattan, once you average it all together, has an FAR of much less than 30. There are a surprisingly large number of very short – even one-story — buildings even within 3-4 blocks of Grand Central). The point for me is not so much whether it is possible, but whether it is desirable.

    Glazer in another part of his book talks about how the surge in midtown office building in the 1950s coincided with declines in other employment centers around NYC. Was this to New York’s benefit, to have an enormous crush of people descending upon midtown every day, while the 125th street stop is almost deserted and outgoing trains are nearly empty? If New York had revised its zoning code to enact a reasonable height limit in 1950, would we have seen development displaced to other parts of the city? I don’t know, but I think these are at least valid questions to ask. Consider Washington DC’s development pattern in this respect. Are there points at which the costs of additional density exceed the benefits, looking beyond the developer’s bottom line?

    Even Manhattan is undergoing an upper-class baby boom, so even in the US families with children are no longer shunning the city.

    It takes an extraordinary amount of money to afford a spacious single-family building in Manhattan. Those wealthy enough to raise children there and send them to private schools there generally have second homes out on Long Island, or on Martha’s Vineyard, and get to enjoy the best of both worlds. Those of supernatural wealth, such as the mayor, do choose single family homes even in the center of Manhattan:


    I’m sure there are some people who prefer apartment living even where a single-family building of equivalent cost, size and amenities is available, but Glazer does not exclude that possibility (“I am not, of course, describing a universal taste…”). And I agree that it varies by country – Italy has had an apartment-dwelling culture for over 2,000 years, for example, while in parts of northern Europe and in Japan apartments are a relatively recent introduction to all but the largest cities.

    To get higher density, one must build higher. … The census tracts where the residents are upper middle-class rather than rich – generally those in the north or east of the Upper East Side – have residential densities of about 50,000-75,000 per square kilometer. In contrast, the average in Manhattan and Paris is about 25,000, and the densest quarter of Paris has about 40,000.

    In terms of total floor area, again, I agree. But for population density there are other factors at work here, also. Recall that Manhattan’s highest population density occurred in 1910, when there were virtually no skyscrapers, and certainly no residential ones, and the massive apartment blocks of the UES had yet to be constructed. By 1930, after the construction boom years of the 1920s, Manhattan’s population density had fallen by 17%. The growth of middle-class wealth presumably created demand for much larger living quarters. This drove the large apartment blocks, which kept some middle-class families in the city while others preferred “SFDR” and left for the commuter towns. If wealth keeps increasing, increased floor area may be needed just to keep population density at a constant level within a fixed area.

    • Alon Levy

      Transit cities generally want to have huge CBDs (yes, Paris is a partial exception – but look at the rise of La Defense together with the RER…). Look at Tokyo, with its huge employment density in Marunouchi, Hibiya, and other CBD districts. Such patterns grow together with an expansive transit system. The economics of agglomeration favor large office buildings everywhere, even in low-density cities such as Atlanta, but when the city is dense and has a good transit system, this creates very dense CBDs. Trying to limit this just creates economic and environmental problems: Washington is saddled with high office rents, and auto-oriented edge cities.

      In general, to have high transit use and low car use, you want employment to be concentrated in the core. Suburban commercial TOD near train stations is good when it displaces auto-oriented suburban development, but it’ll never have the transit mode share of urban downtowns. Even secondary downtowns that look relatively urban, such as Jamaica and Flushing, have a high car mode share by city standards (more than 50%), and their NIMBYs are as hysterical about parking as suburban NIMBYs are about building height or school integration. The only way out of this mess is to ensure transit serves such secondary centers from multiple directions well. (Although it sounds like an argument for Washington’s Silver Line, it’s not; the Silver Line has little hope of competing with the car for travel between Loudoun County and Tysons Corner. It’s instead an argument for extending transit from Flushing to Jamaica, College Point, and Bayside, and from Jamaica to Cambria Heights and Queens Village, since all of those neighborhoods are of such density that giving up one car is realistic for residents who have better transit options.)

      You’re completely right about wealth, apartment size, and density. I should have made this more clear in the post, but Manhattan south of Harlem and Paris are both comparably rich, so the dwelling sizes should be comparable.

      • ant6n

        “Transit cities generally want to have huge CBD”
        I believe this is wrong. This may be true in the US today, where the transit mode share is relatively small, so it gets more efficient to have a bunch of radial lines all end in one point. But once the transit mode share starts increasing, and the CBD grows more and more, you have the problem that you need huge crush-load capacities – but only during a tiny time frame, in one direction. That means you waste A LOT of capacity overall.

        Polycentral urban structures make much more sense imho. And I am not talking about suburban office parks, but simply multiple employment/activity centers spread throughout the city. Now you have multi-directional transit, meaning the capacity of every line can be lower. And the crush load on the lines is spread more throughout the morning rush.

        This of course means you need transit systems with good area coverage, and possibly non-radial networks – and the willingness for people to transfer.

        From an urban perspective (which you dismiss as ‘aesthetics’, but is really about psychology and quality of living, as well) this would also mean that neighborhoods would be more mixed use. Which I believe makes them more livable and lively – the suburb/cbd duality turns most of the city into a ghost town for a lot of the times.

        • Alon Levy

          It’s not just a US thing; it’s also an Asian thing. Tokyo has multiple activity centers, but its primary CBD still has huge job density; the three central wards have about as many jobs as Manhattan, and like Manhattan they have large portions that are residential or low-intensity. The reference I got this bit about transit cities is Paul Barter’s thesis, but he didn’t invent it. Good off-peak service comes from major entertainment districts and major secondary centers. (In Singapore, also a transit city with a dominant CBD, the busiest subway station serves the biggest shopping mall cluster, on the margins of the CBD.) New York grew the same way. Possibly European cities are different because other than London and Paris they’re not as big, so they didn’t experience the capacity overload that characterizes transit cities.

          Polycentric structures can work, depending on how they’re served by transit. If they’re at the end of a subway line, they’ll be predominantly car-oriented – again, look at Flushing. What could work better is dispersed employment throughout a central region, which is a feature of bus cities, and maybe smaller transit cities; to take a New York analogy, it’d be as if employment were dispersed about evenly throughout Manhattan south of 59th and the Brooklyn waterfront. Another thing that could work is development at junctions in the network: if NJ Transit worked as rapid transit, then Newark would be an excellent transit-oriented secondary center (it already is a major secondary center, but its transit mode share is 25%), and with the correct rezoning so would Secaucus.

          Quality of life is definitely an issue for a single-use downtown. And sure, one advantage of bus cities and walking cities is that everything is close. On the other hand, Midtown is surprisingly nice for a giant collection of office buildings – and even Jane Jacobs noted this, contrasting it with single-use Lower Manhattan. Times Square is hell, but East Midtown is okay around First and Second Avenues.

          • Adirondacker12800

            Times Square is too crowded, no one goes there anymore, kind of hellish?
            You many not like it, the urban planners may not like it but the plebes seem to enjoy it. It has lost some of the um um charm… it had back in the day but to me it’s a lot better than anything east of Fifth has to offer.

          • Matthew

            Times Square is for tourists. That, and people going to the Port Authority. There’s been more and more offices and jobs moving there too. But the people standing around and gaping are tourists. The place is dominated by the usual big franchises.

            Now as for the East side, there’s plenty of stuff to do around Second and Third, just walk up and down those avenues and you’ll see.

          • Adirondacker12800

            Tourists are people too. And people go to Grand Central just like people go to the Port Authority.

  6. Steve S

    Different strokes for different folks, as they say. In Death and Life, Jacobs suggests that every particular neighborhood has a sort of perfect balance of residential density: go too far over, and you’ve got overcrowding; go too far under, and you’ve got…well, something we’re all too familiar with.

    Nabes like the Upper East Side have different density balances than nabes like Soho. Jacobs even notes that the density of Rittenhouse Square (Philadelphia’s Upper East Side analogue) is somewhat lower than the Upper East Side itself, suggesting that Philadelphia balances, as a whole, at a lower density than New York. The same can be seen in the differences between Nathan Lewis’ model Japanese neighborhoods and central Paris. I myself demonstrated that a neighborhood of single-family detached houses with generous backyards and rear carports can be incredibly dense. So which neighborhood one moves into is based on personal preference. The task of the urbanist is, thus, not to dispute the advantages of one neighborhood or another, but rather to ensure there is enough of a supply of a whole variety of urban neighborhoods to satiate different levels of demand.

  7. Alex

    I would ask what is the density needed for? If it’s needed to confer status to corporations or wealthy individuals, high-rise might be necessary (or maybe just a prominent location will be enough). If it’s needed to provide ridership to support rapid transit, you can maybe get by with mostly 2-3 story buildings (as even highly car-saturated Cleveland and Baltimore do).

    Density is of course a relative term – I know you say you’re not getting into environmental or aesthetic arguments, but if you’re just trying to accommodate demand for locations that convey status, density isn’t what you need, height is. It’s true that if you’re trying to get above a certain density, at some point you’re going to have to build up – but why are you trying to get to that density? That’s when you’re going to have to get into environmental or aesthetic reasons.

  8. Joseph E

    Steve S, I read the post on your site, and I wouldn’t call your solution “incredibly dense”, but it’s not bad, and good enough for acceptable transit service (very frequent buses or fairly frequent light rail).

  9. ant6n

    I disagree with your discussion, but I think it’s mostly relevant only to Manhattan, anyway. If one wants to make more cities sustainable in America, telling suburbanites to build 30 story buildings (with no space in between) ain’t it. It’s more about telling them how spacing dwellings closer, or building compact 2 or 3 story buildings will get you the density where rapid transit can work really well. This is related to the idea of ‘retrofitting suburbia’ to be more sustainable.

    Building higher and higher is a game of diminishing returns, because you need more space between the buildings (otherwise everybody’s in the dark, for bad quality of living), and more utilities within the buildings. Some would argue that density and building heights are almost independent of each other – I wouldn’t go that far. Nevertheless one should ask how much density one needs – and what other goals one should strive for, for example the creation of livability/liveliness/focusing on the street level/aesthetics/just the ability to sell it to suburbanites.

    Just consider that the Plateau, Montreal, one of the densest neighborhoods in Montreal, has about 12K/km^2, mostly with traditional triplexes – it’s the most transit oriented neighborhood of the city. In Berlin, most downtown neighborhoods have densities of 8-14K/km^2, mostly with 5-6 story buildings – yet the city overall has 160+330 km of rapid transit lines for less than 4million people, and 190km of tram.

  10. Benjamin Hemric

    Since some people have brought up Jane Jacobs. Here, for the record, is a quick and brief Jacobs quote from “Death and Life of Great American Cities” (Chapter 11, “The Need for Concentration”) on the purpose of high dwelling densities.

    “. . . proper city dwelling densities are a matter of performance . . . Densities are too low, or too high, when they frustrate city diversity [which is essential, in Jacobs’ opinion, for the long-term health of city districts] instead of abetting it. This flaw in performance is WHY they are too low or too high.” (Page 272, of the Modern Library edition of “Death and Life . . . “)

    Benjamin Hemric
    Wednesday, June 29, 2011, 9:40 p.m.

    • Alon Levy

      The problem with Jacobs on density is that what is considered too low in one area is too high in another. I forget the number she gives as the minimum for net residential density in a diverse neighborhood, but it’s New York-scaled – if I remember correctly, 12 people per acre, or 20,000/km^2. In reality, diverse neighborhoods with much lower densities are normal in pretty much any other city in the world; Manhattan is one of the biggest cluster of very high urban density in the developed world, and it should not be used to draw global conclusions. Even Tokyo, which is generally dense, doesn’t have a single ward over 20,000, but it would be madness to say none of it is Jacobsian. And the part of Tel Aviv I grew up in has about 15,000/km^2, and the only area in Israel that has 20,000 is Bnei Brak, which achieves its density through overcrowding, since its residents are low-income and ultra-Orthodox and have very large families.

  11. Benjamin Hemric

    Alon, I’m not sure if I understand what you wrote (in your comment timestamped 2011/06/29 at 21:17). On the one hand you seem feel you are disagreeing with Jacobs (“The problem with Jacobs . . . “) but, on the other hand, you seem to be actually agreeing with her!

    In her work in general, but particularly in Chapter 11 (“The Need for Concentration”), Jacobs is specifically saying that there are no fixed levels for good and bad density — even in one city, let alone across the country or around the globe. She is saying, rather, that what’s good or bad density depends on what a given density does — how it performs — and thus what’s good, or bad, varies.

    Plus, although I didn’t include this in my quick excerpt, Jacobs also says that what constitutes good or bad density depends on a number of other factors too (e.g., the size of city blocks, the mix of buildings, the mix of uses, etc.) and that you can never just look at density by itself.

    Again, I have to say, the problem seems to me to be that what’s being discussed is not what Jacobs actually wrote, said or did, but rather what some people “say” she wrote said or did (in other words, common myths about Jacobs).

    Benjamin Hemric
    Thursday, June 30, 2011,

    • Alon Levy

      I reread the section in The Death and Life on concentration of people, and Jacobs does cite an absolute figure. (By the way, although the numbers I previously wrote are right per km^2, they’re wrong per acre; I made a unit conversion error.) She suggests 100 dwellings per net residential acre (25,000/km^2), and complains that Lewis Mumford’s proposed density of 100 people per net residential acre is insufficient for urban diversity.

      The reason I’m being hard on her is that she posits that all four of her principles are necessary for a neighborhood to thrive. There’s no way to do three out of four. The problem is, the Old North does have only three; its density is about 15,000 people per km^2, rising to perhaps 20,000-25,000 if you exclude non-residential areas at the neighborhood’s fringe. It does have a lot of problems coming from central planning, but none is even remotely close to what Jacobs mentions. The biggest is that Geddes’ plan mandated buildings to be white, to reflect sunlight better; the materials required are expensive to procure and maintain, and as a result the neighborhood has always been unaffordable for the working class, and nowadays the whitewash has been peeled away, and only the upper class can afford the price of restoration. This distinction between housing that is expensive because it’s in high demand and housing that’s expensive because it’s expensive to provide is crucial for discussions of urbanism, suburbanization, and zoning; it helps explain not just what happens in one area of Tel Aviv, but also why upper-class American suburbs fight density with all their power.

  12. Benjamin Hemric

    PART ONE — Friday, July 1, 2011

    Alon, Hi! Again I hope you don’t mind a dialog format.

    – – – – – – – – –

    Alon wrote:

    Jacobs does cite an absolute figure . . . She suggests 100 dwellings per net residential acre . . .

    Benjamin Hemric writes:

    Alon, I think still think you are still seriously misunderstanding (and thus unintentionally misrepresenting) what Jacobs wrote. While I suggest those who are interested read the Chapter 11 (“Concentration”) in full to see for themselves (and also possible Chapter 7, “The generators of diversity”), here are just some (of many possible) quotes that help demonstrate that Jacobs was not saying what you are saying she said. (Page numbers are from the Modern Library edition. Added emphasis and added text in between brackets is mine, unless otherwise noted — BH).

    A) (from pg. 272)

    What are proper densities for city dwellings?

    The answer to this is something like the answer Lincoln gave to the question, “How long should a man’s legs be?” Long enough to reach the ground, Lincoln said.

    Just so, proper city dwelling densities are a matter of performance. They cannot be based on abstractions about the quantities of land that ideally should be allotted for so-and-so many people . . . . (pg. 272)

    B) (from pg. 272)

    We ought to look at densities in much the same way as we look at calories and vitamins. Right amounts are right amounts because of how they perform. AND WHAT IS RIGHT DIFFERS IN SPECIFIC INSTANCES.

    C) (from pg. 272)

    “Let us [first look at those communities] at the low end of the density scale to understand, broadly, why A DENSITY THAT MAY PERFORM WELL IN ONE PLACE IS POOR IN ANOTHER.

    D) (from pg. 274-275)

    The “in-between” densities [which Jacobs feels are problematic] extend upward to the point, by definition, at which genuine city life can start flourishing and its constructive forces go to work. THIS POINT VARIES. IT VARIES IN DIFFERENT CITIES, AND IT VARIES WITHIN THE SAME CITY depending on how much help dwellings are getting from other primary uses, and from users attracted to liveliness or uniqueness from outside the district.

    E) (from pg. 275)

    Districts like Rittenhouse Square in PHILADELPHIA and North Beach-Telegraph Hill in SAN FRANCISCO . . . can demonstrably maintain vitality at densities of approximately 100 dwelling unit to the net acre. . . . I can find only one city district with vitality that has WELL UNDER 100 dwellings per acre, and this is the Back-of-the-Yards in CHICAGO.

    – – – – –

    Benjamin Hemric writes:

    The following two things should be noted:

    1) Nowhere, as far as I can tell, does Jacobs cite what is generally thought of as an absolute number as a lower limit for successful densities. In fact, I think it’s fair to say that she specifically eschews such absolute limits — they are anathema to her method of “systems analysis.” (And this is true not only in this chapter of “Death and Life . . . ” but in other chapters too.)

    2) NONE of the examples that Jacobs gives of successful districts on the low end of the scale are from New York City — which was your original complaint.

    Benjamin Hemric
    Friday, July 1, 2011, 9:45 p.m.

    • Alon Levy

      I really don’t mind the dialog format. It’s completely normal on the Internet – the only thing you do that’s not normal for blog comments is that you say “Alon wrote:” instead of just putting what I wrote in quote marks, italics, or blockquote tags. It’s an entirely stylistic difference that you shouldn’t need to apologize for.


      1. “I can find only one district with vitality that has well under 100 dwellings per acre” is exactly giving a limit. In the same chapter, Jacobs treats Mumford’s proposal for 100 people per acre with disdain, saying that it implies 35-40 dwellings per acre and that’s simply not enough.

      2. Sure… but the issue is that the neighborhoods her principles like are, or at one time were, very New York-like. I don’t know what she’d say about Tel Aviv’s Old North, or about Tokyo, but by her four principles they’re not dense enough.

  13. Benjamin Hemric

    PART TWO — Friday, July 1, 2011

    Alon wrote:

    The reason I’m being hard on her is that she posits that all four of her principles are necessary for a neighborhood to thrive.

    Benjamin Hemric writes:

    This is demonstrably untrue — although I do not have the time to find the right quotes at the moment. But my recollection is that Jacobs says numerous times in “Death and Life . . . ” that a specific area is successful despite the fact that it lacks one (or maybe even more) of the four generators of diversity.

    – – – – – – –

    Alon wrote:

    The problem is, the Old North does have only three . . .

    Benjamin Hemric writes:

    I’m unfamiliar with Tel Aviv, but the Old North sounds interesting, and I hope you get a chance to write a blog post about it someday (with maps and photos!).

    But with regard to Jacobs, a few things should be noted.

    First, with the title of her book, Jacobs is specifically noting that she is writing about “great” (i.e., large) “AMERICAN” cities. In the book itself, it becomes clear that she is writing about how best to “save” trouble American cities. In fact, she even makes a disclaimer that what she has written is not necessarily applicable in American “towns, or little cities, or in suburbs which still are suburban.” So I think it is unfair to criticize “Death and Life . . . ” as though it was written to be automatically applicable to cities everywhere.

    Second, although I happen to think (and I think Jacobs also thought) that, indeed, much of what she wrote could, oftentimes, be used to better understand other contemporary cities around the globe, still I think it’s pretty clear from Jacobs writings and interviews that she was well aware of the need to be very careful about how one would go about doing that.

    Third, it’s important to define what one’s criteria for “success” and “thrive” are. For instance, a few months ago Tyler Cowen, the economist, claimed that Brasilia was a success. (I’m not sure if he used the word success though, it might have been something else.) But it seems to me, and at least one other commenter also, that his idea of success was not well defined and likely not my idea of a successful city (nor Jacobs’ idea of a successful city, either).

    Benjamin Hemric
    Friday, July 1, 2011, 10:35 p.m.

  14. Benjamin Hemric

    Alon, you write too fast — apparently our comments have crossed!

    – – – – –

    Alon wrote:

    “I can find only one district with vitality that has well under 100 dwellings per acre” is exactly giving a limit.

    Benjamin writes:

    Alon, I don’t think — especially given the context of the remarks (the other quotes) — that most people would consider this as “giving a limit” (with absolute figures, yet).

    But this is one thing that people just have to decide for themselves.

    – – – – – –

    Alon wrote:

    In the same chapter, Jacobs treats Mumford’s proposal for 100 people per acre with disdain, saying that it implies 35-40 dwellings per acre and that’s simply not enough.

    Jacobs wrote in a footnote on page 275 [emphasis hers unless otherwise noted]:

    . . . Mumford . . . writes, ‘Now the greatest function of the city is . . . to permit, indeed to encourage and incite the greatest potential number of meetings, encounters, challenges between all persons, classes and groups, providing, as it were a stage upon which the drama of social life may be enacted, with the actors taking their turn as spectators and the spectators as actors.” In the next paragraph, however he . . . recommends ‘housing . . . at densities not higher than a hundred, or at most, in quarters for childless people, of 125 PERSONS per acre.’ Densities of 100 PERSONS per acre mean dwelling densities in the range of 25-50 per acre. Urbanity and ‘in-between’ densities like this can be combined only theoretically, they are incompatible because of the ECONOMICS [emphasis mine] of generating city diversity.

    Benjamin writes:

    Yes, Jacobs does treat Mumford’s suggestion that (supposedly) densities in the range of 25-50 dwelling units per acre stimulate urban liveliness with disdain. But I’m not sure how this bears on the topic under discussion. 25-50 dwelling units per acre is a long way down from 100 dwelling units per acre. What urban districts are there that have 25-50 dwelling units per acre that also stimulate the kind of (amazing) urban liveliness that Mumford suggests they might?

    – – – – – – –

    Alon wrote [emphasis and added text is mine — Benjamin]:

    Sure . . . but the issue is that the neighborhoods her principles “like” are, or at one time were, very New York-like. I don’t know what she’d say about Tel Aviv’s Old North, or about Tokyo, but by her four principles they’re not dense enough.

    Benjamin writes:

    I don’t quite understand what you are saying here.

    Jacobs principles don’t “like” any neighborhoods. They point out the features of districts in (AMERICAN) cities that have been successful or unsuccessful over time. As pointed out previously, Jacobs does NOT claim that all successful districts possess all four of the generators of diversity. Plus, she was not writing about foreign cities. (See more in my previous comment which was posted after yours.)

    Parenthetically speaking (since non-American cities aren’t really relevant to a discussion of “Death and Life of Great AMERICAN Cities” — see my previous comment), I’m not sure if I understand your density figures for foreign cities. Jacobs uses dwelling units per acre, so other statistics aren’t really helpful. It would be interesting to find out the dwelling units per acre of Tel Aviv’s Old North or of successful urban districts in Tokyo. Although I haven’t been to either city, from general travel photos it’s hard to imagine them having very low figures for dwelling units per acre. (But, again, even if they do, different cultures, etc., are capable of producing different cities.)

    Getting back to the main topic, American cities, I’m not sure what you mean by neighborhoods that “are, or (especially) AT ONE TIME WERE (?), very New York-like.” Jacobs was writing about “Great” “American” cities, so naturally there are going to be many similarities among the successful ones — how different can these districts be from each other? BUT, nevertheless, the fact is that Jacobs specifically points out that 1) successful densities differ from city to city and even within cities, and 2) she points out that the densities of successful districts in other cities are markedly lower than those of the successful districts in New York.

    Therefore, I think most people are likely to see it as extremely offbase “overstatement” to claim that Jacobs was using New York City criteria for cities all over the U.S. (and the world). How different can successful districts be, especially if we are talking about districts in “great” “American” cities? And, are there, in fact, successful urban districts, even today, in American cities that are not includable in such a “stretched” “New York-like” category (with densities around 100 dwelling units per acre)? Which successful American urban districts that are not New York-like (using this stretched categorization) have been/are being ignored?

    But, of course, people will have to make up there own minds on these issues — I just wanted to point out that, contrary to what was said, in her writings Jacobs herself 1) says that the densities of successful districts vary, and 2) she does NOT cite New York City districts when discussing successful urban districts on the lower end of the density scale. Instead, she discusses districts in Philadelphia, Chicago and San Francisco — districts across the entire country.

    Benjamin Hemric
    Friday, July 1, 2011, 11:45 p.m.

    • Alon Levy

      All the neighborhoods I’m naming as counterexamples to Jacobs’ density principle seem to be in the 25-50 dwellings per acre range. The headline numbers refer to people and not dwellings, but the Old North has 60 people per acre (I would guess about 100 per residential acre), which works out to 28 dwellings per acre (46 per net residential). Ironically, it’s less than the net dwelling density of Akirov Towers, which are built like a fortress with no regard for pedestrians but are so tall that they have 56 apartments per acre of compound footprint including adjacent streets.

      The problem with citing principles of urbanity based only on the US is that urbanism is global. Sufficiently many statements about it are universal – “larger cities have longer commutes,” “people tend to travel 60-90 minutes per day and respond to higher travel speed by traveling longer distances,” “modernist projects and Euclidean zoning are pedestrian-unfriendly” – that people who study cities should try to make their statements as general as possible. National statements tend to be lacking – in experience, or in good explanation. Jacobs was looking to a specific class of neighborhoods, which were demographically similar (working class but gentrifying back before the term was commonly used), and therefore shared characteristics such as density. She was contrasting them with urban renewal projects and suburbia, but not with London’s unplanned neighborhoods, or the plethora of other cities where the density she declared “can be combined only theoretically” with urbanity is considered high.

      re: part 2: I’m probably not going to go to Israel for a while, but when I do, I’ll definitely write about it and include photos. You can look at the photos provided on Google Earth (the neighborhood is bounded by the river, the sea, Ibn Gabirol Street, and the single street named at various points Bograshov, Ben Tsiyon, or Marmorek), but too many of them show the urban renewal towers rather than the streetscape.

  15. Benjamin Hemric

    Alon wrote [emphasis mine — BH]:

    The problem with citing principles of urbanity based only on the US is that urbanism is global. Sufficiently many statements about it are universal – “larger cities have longer commutes,” “people tend to travel 60-90 minutes per day and respond to higher travel speed by traveling longer distances,” “modernist projects and Euclidean zoning are pedestrian-unfriendly” – that people who study cities SHOULD try to make their statements as general as possible. National statements tend to be lacking – in experience, or in good explanation.

    Benjamin Hemric writes:

    There are two aspects to this statement that I a disagree with.

    1) Jacobs was interested in a basic understanding (i.e., the underlying principles) of how “great” “American” cities thrive and grow or stagnate and decay, in order to help those “American” cities that were “dying.” I don’t see why she “should” be trying to make her statements as general as possible. It’s quite enough to understand the important phenomenon in question correctly (especially when so many other people seem to have gotten it very wrong). And, it also seems to me (and seemed to Jacobs) that trying to understand one phenomenon (e.g., great American cities) in terms of another (e.g., Israeli cities, etc.) is exactly the way NOT to go about correctly understanding the original phenomenon.

    If someone believes that evidence from other parts of the world (which have, of course, different cultures, different economic systems, etc.) sheds light on, or contradicts, what Jacobs writes about with regard to great American cities, it seems to me that THEY should be the ones to bring up the topic and to make such a claim (and to try and show why they believe their claim to be true).

    2) When an author (i.e., Jacobs, but any author really) says that they are talking about one topic and NOT about another, it seems to me that it is a big misrepresentation of their ideas to say that the author is (supposedly) writing about the very things that they claim not to be writing about!

    If one believes that the original author’s ideas are inapplicable to the topic that one is interested in, a more accurate approach, so it seems to me, is to say that the original author’s ideas are not applicable, in one’s opinion, to the area that one is interested in talking about (and to then explain why).

    – – – – – – – – –

    Alon wrote:

    National statements tend to be lacking — in experience, or in good explanation. Jacobs was looking to a specific class of neighborhoods, which were demographically similar (working class but gentrifying back before the term was commonly used), and therefore shared characteristics such as density. She was contrasting them with urban renewal projects and suburbia, but not with London’s unplanned neighborhoods, or the plethora of other cities where the density she declared “can be combined only theoretically” with urbanity is considered high.

    Benjamin writes:

    Again, it seems to me that these remarks reflect a misunderstanding of what Jacobs was writing about (and thus seem to me to be an unintentional misrepresentation of her work).

    Jacobs was NOT at all “looking” to a specific class of neighborhoods. Jacobs was looking at those districts (not all of which, it’s important to note, were even residential “neighborhoods”) that succeeded over time and continually self-regenerated themselves, and at those districts (not all of which, again, were residential) that had trouble succeeding over time (and were not self-regnerating themselves). Yes, many of the successful neighborhoods had a period in which they were poor working class neighborhoods (how else can one examine the “unslumming” of a poor residential neighborhood?), but NOT all of them were residential or even poor (some of the successful districts had always been successful).

    With regard to London’s unplanned neighborhoods: It’s unclear to me how a study of London’s unplanned neighborhoods are supposed to contradict Jacobs work — especially since Jacobs was specifically concerned with great American cities.

    With regard to low-densities and urbanity: Again, which districts in AMERICAN cities supposedly contradict Jacobs statement in 1961 that “Urbanity and [dwelling densities in the range of 25-50 per acre] ‘in-between’ densities like this can be combined only theoretically, they are incompatible because of the ECONOMICS [emphasis mine — BH] of generating city diversity.”

    – – – – – – – –

    Benjamin Hemric writes:

    Generally speaking, it seems to me that for some reason you have greatly misunderstood Jacobs’ writings (perhaps because of a different cultural background or a different set of main interests?) and are thus criticizing things that Jacobs never wrote or said. However, I greatly appreciate the opportunity you and your blog have provided to “clear the air” and to present Jacobs’ own words in her defense; and I hope that people who are interested in this topic will actually go to her books themselves and make up their own mind as to what it was that she was saying and to what extent it was, or was not, valid.

    Benjamin Hemric
    Sat., July 2, 2011, 12:05 p.m.

    • Alon Levy

      I’m pretty sure Jacobs herself did not think she was being so parochial as to say nothing of interest outside the major US cities of the early 1960s (and even then… how dense was the Castro, anyway?). In fact in The Economy of Cities and Cities and the Wealth of Nations she made an effort to branch out and say global things about import replacement, megaprojects, and urban geography; she did not talk about urban design as much, but she did take the same bottom-up, anti-hierarchical approach.

  16. Benjamin Hemric

    Alon Levy wrote:

    I’m pretty sure Jacobs herself did not think she was being so parochial as to say nothing of interest outside the major US cities of the early 1960s . . . In fact in “The Economy of Cities and “Cities and the Wealth of Nations” she made an effort to branch out and say global things about import replacement . . .

    Benjamin Hemric writes:

    As far as I can tell (having read all of her major books and probably most of her interviews) there is no basis whatsoever for claiming that Jacobs was not just talking about “great” “American” cities. Unless some kind of genuine evidence is presented to the contrary, saying otherwise seems to me to be sheer, and unwarranted, speculation.

    Yes, in her later books she is not just talking about America, but these books are, obviously, different books about different topics — topics that warranted a broader approach.

    When discussing the work of an author, why not discuss what the author actually wrote? Why speculate and put words into an author’s mouth — and then go on to criticize the author for “saying” them?! Why not just judge an author’s work by what the author actually wrote?

    (If one wants to discuss the broader applicablity of an author’s work, one can certainly do this on one’s own, without dragging the author into it and putting words into the author’s mouth that the author never said.)

    Benjamin Hemric
    Sunday, July 3, 2011, 9:50 p.m.

    • Alon Levy

      For one, it’s the same approach as in later books. For another, the Garden City reformists who Jacobs criticized came from London; if her work is only applicable to the US, then why attack Ebenezer Howard rather than the people who imported his ideas to the US?

  17. Benjamin Hemric

    Alon Levy wrote:

    For one, it’s the same approach as in later books.

    Benjamin Hemric writes:

    Not sure what you mean here. But the fact that Jacobs tackled broader topics later in her career doesn’t really say anything about her earlier work. In her first book, Jacobs is pretty clear what the subject matter is. The fact that she later choose broader topics has no bearing on the meaning of her earlier work — especially in contradicted the pretty clear words that she uses delimited the subject matter of her first book.

    – – – – –

    Alon Levy wrote:

    For another, the Garden City reformists who Jacobs criticized came from London; if her work is only applicable to the US, then why attack Ebenezer Howard rather than the people who imported his ideas to the US?

    Benjamin Hemric writes:

    In “Death and Life . . . ” Jacobs criticizes the impact that the Garden City movement had on “great” “American” cities. It was 1) actually an anti-city alternative to begin and 2) its principles were adapted to cities with highly negative effects.

    Don’t have time at the moment to directly quote Jacobs, but for those who are interested in reading for themselves what Jacobs actually had to say, she discusses, directly and indirectly, the impact of the Garden City movement on “great” American cities on pps. 23 – 34.

    Benjamin Hemric
    Sunday, July 3, 2011, 11:56 p.m.

  18. Benjamin Hemric

    July 19, 2011 – PART ONE

    Hi, Alon. Sorry for this very belated comment, but I didn’t have a chance to submit it earlier.

    I reread some of Jacobs a few weeks ago and I can see more clearly now why you interpretated her remarks about the four generators of diversity as you did. However, I still think that she was saying something different and I’d like to briefly (!) explain why. So here’s some belated comments on the topic.

    – – – – – –

    Alon Levy wrote way back on 2011/07/01 at 13:28 [with the added emphasis and added text within brackets being mine — BH]:

    The reason I’m being hard on [Jane Jacobs] is that she posits that all four of her principles [i.e., the generators of diversity] are necessary for a neighborhood to THRIVE. There’s NO WAY to do three out of four [and still have a neighborhood that is going to thrive].

    Benjamin Hemric writes:

    Rereading the relevant sections of “The generators of diversity” a while back (I’ve been too
    busy to write-up a comment until now), I could see why someone might easily come up with such an interpretation. HOWEVER, it still seems to me that this is an incorrect interpretation of what Jacobs has written and, for the record, I’d like to briefly explain why. First, though, let’s look at the actual relevant statements in “The generators of diversity” chapter.

    Jane Jacobs wrote [all page numbers are from the Modern Library edition, and all added emphasis is mine unless otherwise noted — BH]:

    “To generate EXUBERANT diversity in a city’s streets and districts, four conditions are indispensable . . . ” (page 196)

    “The purpose of explaining [the four generators of diversity] one at a time is purely for convenience of exposition, not because any one — or even any three — of these necessary conditions is valid alone. ALL [this is italicized in the book] four in combination are necessary to generate [*SEE FURTHER BELOW*] city diversity; the absence of anyone of the four FRUSTRATES a district’s potential.” (Page 197)

    Benjamin Hemric writes:

    Before discussing these Jacobs quotes in Chapter 7, however, it’s important to note that elsewhere in “Death and Life . . . ” Jacobs herself discusses streets and districts that are, essentially, “thriving” (to use Alon’s word) BUT are nevertheless missing one of the generators of diversity. For instance, I think it’s fair to say that Jacobs sees the “Back-of-the-Yards” as a thriving district, despite it’s having a density that is on the low side (which she, herself, points out). Also, in Chapter 9, “Some Myths About Diversity,” Jacobs mentions two streets in Greenwich Village that are “thriving” (to again use Alon’s word) despite having blocks that are much too long.

    Here is what Jane Jacobs wrote regarding the above:

    A) “I can find only one city district with vitality that has well under 200 dwellings per acre and this is the Back-of-the-Yards in Chicago.” (page 275)

    B) “Sometimes diversity of uses, combined with diversity of age, can even take the curse of monotony off blocks that are far too long . . . An example of this kind of diversity is Eleventh Street between Fifth and Sixth Avenues in New York, a street admired as both dignified and interesting to walk on.” (pp 296-297)

    C) “One of the blocks of Greenwich Village which happens to be spontaneously upgrading itself in attractiveness, interest and economic value, happens also to have a funeral parlor on it as this is written, and has had for years.” [In this part of the book, Jacobs is actually rebutting the supposed blighting effect of certain uses; but although Jacobs doesn’t name the block in question, one can tell from her description that it’s another one of Greenwich Village’s very long blocks, this time W. 13th St., between Sixth and Seventh Avenues.] (page 304)

    Benjamin Hemric
    Tuesday, July 19, 2011 9:20 p.m.

  19. Benjamin Hemric

    July 19, 2011 – PART TWO

    Benjamin Hemric writes:

    So, given the totality of Jacobs writings, what is the meaning of the quotes cited from Chapter 7 on the four generators of diversity?

    Briefly put, Jacobs is saying that in order for a street or district to have the BEST chance to generate diversity and to “thrive,” it has to have all four of the generators. And, as she mentions just shortly afterward, “the absence of anyone of the four FRUSTRATES a district’s potential.” In other words, districts can “thrive” without one of the four generators, but the absence of one of the four generators is holding them back from thriving even more.

    Along these lines, note further what she has to say about the Back of the Yards.

    Jacobs wrote:

    “But even the Back-of-the-Yards shares some of the liabilities of visual monotony, small, everyday inconvenience, and fear of strangers . . . that go virtually always with “in-between” [i.e., relatively low, urban] densities.” (page 275?)

    Benjamin Hemric writes:

    So, although the Back of the Yards has “vitality,” it’s potential has nevertheless been frustrated by the absence of one of the generators of diversity: high densities.

    Jacob’s is not saying that the absence of a generator “kills” off a district, or that it makes it impossible for such a district to succeed or to “thrive” – just that it is an impediment and should be recognized as an impediment – and not an asset (see more about this further below). In other words, she’s not making any guarantees about the success of districts that have only three of the generators. They can be successful, but she isn’t guaranteeing that if a district has only three of the generators that’s enough to ensure it’s success.

    Note further that Jacobs isn’t even making any guarantees about districts that actually possess all four generators.

    Jacobs wrote:

    “Given these four conditions, not all city districts will produce a diversity equivalent to one another . . . but given the development of these four conditions . . . . a city district should be able to realize its best potential, wherever that may lie. Obstacles to doing so will have been removed . . . . they will get their best chance. (page 197)

    Benjamin Hemric writes:

    Looking at Jacobs’ actual writing, I think one sees that Jacobs is usually rather measured and cautious in what she writes in general and in what she has written about the four generators of diversity in particular.

    In terms of her usually very cautious writing, though, she may have made a rare slip of the pen, so to speak, by leaving out a qualifier like “exuberant,” or “genuine,” etc. in the spot where I’ve placed [*SEE FURTHER BELOW*] in the quote taken from page 197. But, then again, “Death and Life . . . ” is a book intended to be readable for popular audiences. It’s not a journal article, or a legal brief or a credit card agreement. So I think she qualifies her statements enough elsewhere on the page and elsewhere in the book. Which is why I think one has to look at the totality of what she has written.

    One may also ask, however, if Jacobs is being so extremely cautious in her writing (as I am arguing) about the four generators of diversity, what’s the point of her very extensive discussion of them? In other words, what’s the point of discussing them in such detail if there are so many qualifications and exceptions?

    One point of her discussion is that these are (in her opinion) the four generators of diversity and, furthermore, diversity is very important (in her opinion) for urban health over the long run. Thus these are the results that she found in her search for a better understanding of city vitality, and it’s important for her to report the results of her investigations.

    Another point to her discussion, it’s important to note, is that the four generators of diversity and urban health are the EXACT OPPOSITE of the orthodox prescriptions for urban health: wiping out all old buildings, creating superblocks, and building low-density, single-use districts in their stead. So even in her highly qualified statements, Jacobs is saying that “orthodox” prescriptions for urban health are going in exactly the opposite direction of where they should be going – they’re prescriptions for making things worse rather than better.

    Furthermore, the point is that when we want to help those districts that are not thriving, Jacobs is saying that it’s important to look to see if they are missing any of the generators of diversity. There is a very good possibility, according to Jacobs, that they are.

    Benjamin Hemric
    Tuesday, July 19, 2011 9:25 p.m.

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