High Quality Content by WIKIPEDIA articles! U.S. Route 30 (US 30) is a major east–west U.S. Highway which spans 330 miles (530 km) across the state of Iowa. It is the longest primary highway in the state and is maintained by the Iowa Department of Transportation (Iowa DOT). The route in Iowa begins at the Missouri River crossing at Blair, Nebraska, and ends at the Mississippi River crossing at Clinton. Along the way, it serves Denison and Carroll in western Iowa, Boone, Ames, and Marshalltown in central Iowa, and Tama, Cedar Rapids, and DeWitt in eastern Iowa. Cutting across the central portion of the state, US 30 runs within close proximity of the Union Pacific Railroad`s Overland Route for its entire length.