- 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 2011 was 113,600 vehicles per day. For traffic counts by county or city click here.
- Motor vehicles on Iowa's public roads traveled an estimated 31.41 billion miles in 2011.
- 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 61.8 percent of all vehicular traffic. (2011)
- The weighted average daily traffic count on Iowa's Interstate Highway System is 22,493 vehicles in rural areas and 45,698 in municipal areas. (2011)
- The weighted average daily traffic count on rural county roads is 161 vehicles. The weighted average on municipal streets is 1,235 vehicles. (2011)