Iowa is bordered by six states, though only three are traditionally "Great Plains":
| State | Direction | Region |
|---|---|---|
| Minnesota | North | Upper Midwest |
| Wisconsin | Northeast | Great Lakes |
| Illinois | East/Southeast | Midwest |
| Missouri | South | Midwest/Plains transition |
| Nebraska | West | Great Plains |
| South Dakota | Northwest | Great Plains |
Kansas does not border Iowa (Missouri separates them).
Rivers define most borders: Mississippi (E), Missouri (W), Big Sioux (NW).