Source: BTS.
Density and Car Use in North American Cities, 1991
The strong association (R2=0.694) between density (number of people per hectare) and car use (average number of kilometers driven per capita per year) indicates that modal preference, urban form and density are closely related. While for Houston and Phoenix, dispersed developments and low densities leaves little choice other than car usage, denser locations such as New York, Toronto and Montreal have more alternatives. For instance, between 1950 and 1990 while the population of Chicago grew by 38%, its built area grew by 124%. The challenge of many cities wishing to address car dependency is to offer development plans that meets the mobility demands of their populations, while increasing density.