I’ve argued before that we can’t be serious about combating global warming until we recognize that population density is key–the key–to reducing energy use. Don’t worry: as Atrios likes to joke, I’m not trying to turn your suburb into mid-town Manhattan. But areas that are amenable to high density, such as those that have extensive public transit and the essentials of life (including commercial ones) within walking distance should have high densities. Mind you, someone like Matthew Yglesias might just want to turn your suburb into Manhattan.

In fairness to Yglesias, he does what a lot of policy wonks inherently do: he compares what he knows (New York City and European cities) to the U.S. mecca of wonkdom, Washington D.C. (D.C. does have a lot of screwed up urban policies, some of them justifiable, some of them not). In particular, the shibboleth of D.C. policy wonks is the restriction on building heights to eight stories, so as not to overshadow the Washington Monument (aside: this does have the advantage of being exposed to direct sunlight for more than a few hours every day. Just saying).

What this mindset leaves out is a lot of other successful cities that are very dense also don’t require a lot of skyscrapers either, such as Boston. More on how that happens in a bit, but this allows me to discuss this excellent post over at Bostonography that has a lot of cool graphics. One such graphic looks at density essentially block by block:

To orient you, the square section with a lake in the middle is the Boston Public Garden (not the section right by “Boston”–that’s the Fens). I’ve left off the southern parts of the city (Jamaica Plain, Roxbury)–more to about that in a bit. Directly to the west of the Public garden on the street grid is Back Bay, directly to the North, Beacon Hill. The North End is to the east of Beacon Hill. The South End is directly south of Back Bay (shocking). South Boston (Southie) is the neighborhood in the bottom right corner.

The colors indicate density. Grey means non-residential, while the darkest shade of blue (almost black) means >40,000 people per square mile, the next lightest shade is 30,000-40,000 per square mile. The bright teal color is 5,000-10,000 per square mile.

So let’s look at the two swankiest Boston neighborhoods, Beacon Hill and Back Bay. Virtually all of Beacon Hill has a density of greater than 40,000 per square mile. Large sections Back Bay are also that dense. The lighter teal sections of Back Bay are along Newbury Street which is a shopping and eating district that brings in tourists–this is mixed zoning that has stores that attract people from outside the city (there’s also an error that results in underestimating the densities. There’s a thin strip running down the middle that’s flanked by two streets; that’s Commonwealth Park, in the middle of Comm. Ave.–nobody lives there). The North and South Ends, also nice neighborhoods, are very dense too. Very dense living!

We can also look for areas that are as dense as the Manhattan average, shown in blue:

Here we see that Beacon Hill, parts of Back Bay and the South End, the North End and Bay Village are very dense. Yet contra Yglesias and the other wonks, these areas have very few skyscrapers. In fact, most buildings have five stories (four floors and a basement), with a smattering of taller buildings that max out at fourteen stories (and most of the taller buildings aren’t that high, more like nine stories). So how does Boston do it?

Well, obviously, apartments aren’t that large, which is the case for most cities. But besides that, Boston has two things going for it that most other cities don’t have: narrow streets and sidewalks. Not a lot of space is wasted in residential areas. Sidewalks at most are about nine to ten feet wide, and skinnier in other places (e.g., Beacon Hill). The streets typically are very narrow–about ten Mad Biologist paces (my pace length is about average)–if you factor in parked cars, add about four paces. Not only does this making walking around easier, but the real estate is used to house people, not air or cars. That allows much higher densities (although it makes drivers crazy at times) without skyscrapers.

Even though Boston’s average density is low, this is a consequence of Boston’s role as a regional cultural, educational, and political center, which means that about half of the city is neither business nor residential; in other words, Boston has a relatively low amount of residential real estate. If you look at the larger images in the Bostonography post, the other problem is that neighborhoods such as Jamaica Plain and Roxbury just aren’t very dense (neither are the adjacent municipalities of Newton and Brookline).

So I don’t want to turn your suburb into Manhattan, just Back Bay or Beacon Hill.

I kid, although one could do a lot worse than either of those neighborhoods….