| Iowa Primary Highway System | |
|---|---|
 Highways that changed jurisdiction around 1980 Removed highways Renumbered highways Added highways | |
| System information | |
| Notes | Primary highways in Iowa are generally state-maintained. |
| Highway names | |
| Interstates | Interstate X (I-X) |
| US Highways | U.S. Highway X (US X) |
| State | Highway X (IA X or Iowa X) |
| System links | |
Beginning in 1979 and lasting through the early 1980s, a series of agreements between the Iowa Department of Transportation and individual county boards of supervisors led to a mass transfer of jurisdiction of several state highways in Iowa. County boards of supervisors were asked to convene functional classification boards in order to review the classification all of the highway miles within each respective county. Control of roads that were classified as trunk roads or trunk collector roads were transferred to the counties, while roads classified as arteries or arterial collectors were transferred to the state department of transportation. The vast majority of transfers took place in 1980.