| United States Numbered Highways of the Iowa Primary Highway System | |
|---|---|
 .svg)  Highway markers from different years for former US 32 (1926), US 75 (1961) and current US 151 (1971) | |
 U.S. Highways in Iowa highlighted in red | |
| System information | |
| Length | 3,627 mi (5,837 km) |
| Formed | November 11, 1926[1] |
| Highway names | |
| US Highways | US Highway nn (US nn) |
| System links | |
- ^ Bureau of Public Roads & American Association of State Highway Officials (November 11, 1926). United States System of Highways Adopted for Uniform Marking by the American Association of State Highway Officials (Map). 1:7,000,000. Washington, DC: United States Geological Survey. OCLC 32889555. Retrieved November 7, 2013 – via Wikimedia Commons.