It begins where South Dakota Highway 46 crosses the Big Sioux River into Iowa north of Hawarden.

It continues east through Granville and meets Iowa Highway 143 before entering Paullina.

After Paullina, Iowa 10 then runs concurrent for 5 miles (8.0 km) with U.S. Highway 59.

Iowa 10 turns slightly southeast to go through Peterson, then continues east until intersecting U.S. Highway 71.

Prior to the construction of the bypass, the two routes which Iowa 450 connect intersected in Alton.