- The busiest spot on Iowa's roadways is on I-235 in Des Moines between 56th Street and 42nd Street where the average daily traffic in 2014 was 127,100 vehicles per day. For traffic counts by county or city click here.
- Motor vehicles on Iowa's public roads traveled an estimated 32.33 billion miles in 2014.
- The Primary Road System, which is managed by the Iowa DOT, represents 8.2 percent of the total road mileage in the state. However, these roads carry 62.8 percent of all vehicular traffic. (2014)
- The weighted average daily traffic count on Iowa's Interstate Highway System is 22,929 vehicles in rural areas and 44,840 in municipal areas. (2014)
- The weighted average daily traffic count on rural county roads is 163 vehicles. The weighted average on municipal streets is 1,321 vehicles. (2014)