Recently I wrote a post about "walkability" in which I asked the readers of Massahoma, Oklachusetts to visit the WalkScore website to determine how walkable their neighborhoods are. Almost without fail, the addresses with the highest WalkScores were in cities with the highest population densities. This does not surprise me at all, because a high population density means more people concentrated into a particular area means greater demand for the goods and services that businesses provide, and this demand is more frequent and consistent because it can come in the steady form of foot traffic (as opposed to only coming by car), which means that land can be developed for other, more significant purposes than parking. High population density equals foot traffic equals consistent demand equals business development. Add it all up and you have thriving urban areas where people live, work, study, shop, and play. Population density is what drives mixed-used development. And as Blair Humphreys notes in his most recent post on imagiNATIVE america, streetcars can play a big part in the creation of this density and development.
Check out these numbers from the 2000 Census Data: of the three major cities I lived in (Oklahoma City, Cincinnati, and Boston), Boston has the largest population at 608,352 and the highest density at 12,172.3 people per square mile, while Cincinnati has the smallest population at 332,458 but the second highest density at 4247.2 people per square mile. Oklahoma City, meanwhile, has a population of 547,274 but a density of 833.8 people per square mile.
Let's put these figures into larger perspective. Of the 263 biggest cities in the US (cities with populations over 100,000), Boston ranks 21st, OKC 31st, and Cincinnati 56th. But when ranked by population density, Boston is 10th, Cincinnati is 76th, and Oklahoma City is 258th out of 263. I know Oklahoma City doesn't have the natural boundaries like Boston and Cincinnati have (the Charles River, the Bay, the Ohio River, etc.), and I know Oklahoma City went on what Steve Lackmeyer in his book OKC Second Time Around calls an "annexation spree" in the 1950s that saw its land area jump from 80 to 475 square miles by 1961 (today it covers 620 square miles and is the second largest major metropolitan area next to Jacksonville, Florida). I also know that this annexation spree happened at the same time Oklahoma City's extensive streetcar system and interurban passenger rail service was being dismantled (today no such service exists, though many people are pushing hard to have streetcars included in MAPS 3). For an in-depth account of OKC's streetcar past, start with Doug Loudenback's "Okc Trolleys Part 1". For photos of downtown's long gone Interurban Terminal, see the spread at Rezone OKC.
I know these things, but I don't have to be an urban planner to realize that 258 out of 263 is absurd. The number isn't entirely accurate, since there is more rural square footage in Oklahoma City than urban square footage. But even if you deannexed the rural areas (and generated a political firestorm in the process) and thus reduced its total square footage, OKC's population density would still be lower than it would have been if not for four decisions that eroded the city's core:
1) Unchecked expansion of city limits;
2) Development outward instead of inward;
3) Disappearance of streetcar and passenger rail service;
4) "Clearance and Redevelopment" of the urban landscape through Urban Renewal (to see what was lost, check out these maps, courtesy once again of Blair).
If Oklahoma City had restricted its territorial growth, concentrated its development, and preserved its architectural buildings and transportation infrastructure, then we'd be in a different league right now. For the most part, this is what Boston did. But OKC didn't, and so every civic decision we make from now on must somehow address our critical lack of population density.
Stay tuned for some satellite images that illustrate this problem...and a reader contest!