It ran from the Missouri state line, where it connected to Route 15 to Iowa 2 in Milton.

The route ceased to exist on July 1, 2003, when the Iowa Department of Transportation turned over 700 miles (1,100 km) of state highways that mostly served local traffic.

The highway ran over relatively flat terrain, only undulating approximately 40 feet (12 m) over the length of the route.

[4] In this case, Iowa 23 in Van Buren County was renumbered to match Route 15 in Missouri.

That route was previously Iowa 44 and was renumbered to match Minnesota State Highway 15.