 U.S. Highway 18 | ||||
|---|---|---|---|---|
 US 18 highlighted in red | ||||
| Route information | ||||
| Maintained by Iowa DOT | ||||
| Length | 311.750 mi[1] (501.713 km) | |||
| Existed | November 11, 1926[2]–present | |||
| History | Primary Road 19 from 1920–1926[3] National Parks Pike registered in 1920[4] | |||
| Major junctions | ||||
| West end |  US 18 near Canton, S.D. | |||
| East end |  US 18 / WIS 60 at McGregor | |||
| Location | ||||
| Country | United States | |||
| State | Iowa | |||
| Counties | ||||
| Highway system | ||||
| ||||
U.S. Highway 18 (US 18) is the northernmost east–west United States Numbered Highway in the state of Iowa. As with all state highways in Iowa, it is maintained by the Iowa Department of Transportation (Iowa DOT). It enters the state by crossing the Big Sioux River between Inwood and Canton, South Dakota. It travels about 312 miles (502 km) and connects Spencer, Mason City, and Charles City. The highway leaves the state via the Marquette–Joliet Bridge over the Mississippi River at Marquette. Prior to becoming a U.S. Highway, the route US 18 follows was known as Primary Road No. 19 and the National Parks Pike.
- ^ Cite error: The named reference
DOTGISwas invoked but never defined (see the help page). - ^ 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.
- ^ Official Auto Trails Map (Map). 1:1,081,344. Rand McNally. 1921. p. 330-331.
- ^ "Iowa Registered Routes". Iowa Department of Transportation. Retrieved September 15, 2011.