Density and Skyscrapers

I feel like a lot of readers are misunderstanding the argument Ed Glaeser is making concerning the value of skyscrapers. Glaeser is arguing, in a nutshell, that density is valuable and so society should embrace taller buildings. People then respond, “But you don’t have to build tall to be dense…just look at Paris!” Here’s Richard Green:

I just read Ed Glaeser’s Atlantic piece on skyscrapers (which is excerpted from his new book on cities that I need to read).  I agree with nearly everything he says, particularly about the need for tall buildings in Mumbai, but I also think it is worth mentioning that one can get a lot of density without a lot of skyscrapers.  The municipality of Paris has a residential density of about 54,000 people per square mile; Manhattan has a residential densisity of about 71,000 people per square mile.  Paris has about 1.7 million workers, while Manhattan has about 2.1 million workers.  Yet as Ed notes, Manhattan has lots of skyscrapers, and Paris has few, and almost none outside of Le Defense.

This comparison encourages a lot of people (not necessarily Richard Green) to decide that we don’t need skyscrapers. Defenders of the Washington height limit often fall into this category. But there are two points worth making in response to this. One is that it would be harder to build Paris in America than it would be to build Manhattan. Paris’ tiny streets are more hostile to the automobile than anything in the US, including Manhattan. And Paris has relatively tall buildings over a vast area; it’s easier for me to imagine Washingtonians tolerating 30-story buildings downtown than 10-story buildings in a central neighborhood like Brookland. If you need 10-story buildings in every little Brookland-like neighborhood to generate the same density you achieve with 30-story buildings in a central business district, then you can basically forget about generating high densities in American cities. The NIMBYs are just too strong.

The second point is that Glaeser isn’t directing people to go out and build skyscrapers. He’s not a planner. He’s merely saying that, yes, allowing developers to meet demand with supply will often yield tall buildings, and that’s a good thing. It will increase densities relative to the alternative, supply-limited case, and it will improve affordability relative to the alternative, supply-limited case. People who read Glaeser lauding density and who go on to tout the advantages of Paris get his argument precisely backwards. Because density is good, it’s costly — in terms of the metropolitan economy and affordability — to adopt Parisian limits on growth. Unless your city is one of the architectural jewels of the modern world, and if you live in America it isn’t, you should work very hard to avoid such constraints.


  1. Mixner says:

    Your claim that density is good ignores the problems created by density that cause people to support laws that limit it — congestion, crowding, noise, pollution, loss of privacy, expensive real estate, etc. Proponents of density seem to think that if they just don’t mention these problems people will somehow forget about them. I don’t think that’s going to happen.

  2. Keith says:

    I would love to understand the rationale behind Mixner’s theory that density actually creates expensive real estate. If that were the case, maybe NYC should just lop off every skyscraper at 10 floors high and then magically real estate will be cheaper in New York! The reality is that land is valued for its proximity to goods (climate, jobs, recreation, schools, transport) and there are many cities where restrictions on the supply of land through density limits results in more expenisve real estate in that city. Again, no proposal that I’ve heard of on this topic insists on forcing landowners to build at higher density. It’s just that it would make economic sense for some of those landowners to develop greater density in order to divide the cost of land among more users if they were allowed to do so.

  3. Mixner says:

    I would love to understand the rationale behind Mixner’s theory that density actually creates expensive real estate.

    The price of a resource tends to increase with demand. Higher density, by definition, means more people competing for each square foot of land. Since real estate consumes land, higher land prices tend to mean higher real estate prices. It’s not exactly rocket science.

    And it’s not just expensive real estate. It’s all the other problems of density I listed too.

    Mixed-use development, in which residential development is mixed in with commercial development, tends to further increase the price of housing. Home buyers are competing for land with commercial businesses that can afford to pay more.

  4. Charlie says:

    Keith: A city with no downtown height limit will tend to have inflated land costs that reflect the potential of a very tall building on each lot. Very tall buildings, moreover, due to their high cost of construction combined with the high cost of land, will need to contain high-priced units if the developer is to turn a profit. But there is a limited market for very pricey high rise condos, which among other reasons will constrain the amount of built space which will be supplied under this arrangement.

    The height-limited city, by contrast, has lower land prices, making it economical to construct stick-built mid-rise apartments which are much cheaper, on a per-unit basis, than the skyscraper. Lower development costs, in turn, mean that more total development will take place. Even more so since the market for cheaper units is much larger, so the total supply of units is likely to be greater than in the previous scenario.

    Of course the mid-rise but dense area may, in the long run, experience greater comparative demand due to its livability — but I wouldn’t want to be placed in the position of arguing that we should aim to create density in unpleasant, less-livable forms in the name of affordability.

  5. Keith says:

    In the context of this discussion, which is about laws that pertain to building restrictions, the only possible change in the supply/demand balance is on the supply side. The demand doesn’t change simply because a law would allow higher density – the demand is already there. Artificially limiting supply results in downtown DC having the highest commercial real estate rents in the nation, with a corresponding lack of diversity in employment (mostly law firms and lobbying organizations that value the proximity to government the most).

    The confusion may lie in the fact that yes, land prices may rise in certain areas due to a change in zoning. However, land prices would decline in other areas, as formerly commercial areas can revert to residential, or high residential to low residential, etc. Furthermore, since the areas that see an increase in land prices would tend to be more dense than before, the land price per unit of usable space would actually decline, and that is what we should really care about if we are talking about the price of real estate.

  6. Mixner says:

    We “artificially” limit the supply of housing in a variety of ways for aesthetic, practical, environmental, and health/safety reasons. Laws that set aside land for roads, sidewalks, parks and other public spaces obviously limit the supply of housing that can be built. So do health and safety regulations, historic preservation laws, environmental protection laws, and so on. People value other things besides housing. The fact that you personally don’t like certain laws that have this effect (the bulding height restriction in DC, single-zoning or whatever else it may be) doesn’t mean they are bad laws or that they do not serve the general interest.

  7. Mitch says:

    Most cities in america have a one or two story cap in residential neighborhoods. That is the difference. if the cap was raised to ten stories or so you would see much denser developments in the states. mixed use buildings under 13 stories are the answer. When you get skyscrapers you need larger roads and trucks to services them. That is why higher densities are achievable with smaller buildings. Its counter intuitive but it makes sense when you think about it.