Economists and urbanists have long argued that density plays a key role in innovation and economic growth. As important as it is, density is a tough thing to measure. Metros come in different shapes as well as sizes: Some have more concentrated populations near the center, others are more continuously sprawling. Yet, density is typically measured rather crudely by simply dividing the total population of a city or metro area by its land area.
A new report [PDF] from the U.S. Census Bureau helps to fill the gap, providing detailed estimates of different types of density for America's metros. This includes new data on "population-weighted density" as well as of density at various distances from the city center. Population-weighted density, which essentially measures the actual concentration of people within a metro, is an important improvement on the standard measure of density. For this reason, I like to think of it as a measure of concentrated density. The Census calculates population-weighted density based on the average densities of the separate census tracts that make up a metro.