The Deception of Density

One thing that many planners, economists, and urban reformers agree on these days is that density is a good thing. But there’s something deeply deceptive about density: Far from being a straightforward statistical measurement, it’s actually difficult to define and easy to manipulate. Thinking carefully about the flaws inherent in measuring density can encourage us to better articulate what it is about density that we actually value—and to emphasize those outcomes, rather than raw density itself, as objectives of foresighted urban design.

The problem with density as a statistical measurement arises from the fact that we have to make a choice about what geographic unit to use as the denominator in the formula of people divided by area which gives us density. That choice can lead to some strange flukes. If we measure the density of two people sleeping in a 40-square-foot tent in the wilderness of Alaska at the resolution of one tent unit, we get a density of 1.4 million people per square mile, or about 20 times the density of Manhattan. Meanwhile, the most recent census found 25 people living in New York City’s Central Park, giving the park a density of just under 19 people per square mile, slightly more rural than Idaho.