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Figure 2

Population Density and VMT in 1995

Source: Federal Highway Administration, Highway Statistics 1995 (Washington: FHwA,

1996), Table HM-71.

For comparison, in Figure 2 shows that the correlation

between population density and vehicle-miles traveled (VMT)

per square mile is strong.  New Urbanists would predict that

VMT would tend to decline in the 391 most densely populated

areas in the United States, but the data indicate otherwise.

Here, a clear correlation is evident: higher densities lead

to more auto travel.  Unless those higher densities are

accompanied by higher road capacities, higher densities also

lead to more congestion.

Even the most optimistic New Urbanists say that in-

creased density reduces only the share of trips using autos,

not the total number of miles driven.  One study predicts

that doubling density will reduce the auto's share of trips

by 20 to 30 percent.42  But if density doubles from, say,

2,000 people to 4,000 people per square mile and the auto's

share of trips declines by 30 percent, there will still be

1,400 trips generated for every 1,000 trips before the

density increase.