| 1922 – present|
| 40.2 km|
| US 169/Route E east of Union Star|
US 169 northwest of Gower
Missouri Route 31 Wikipedia
Route 31 is a highway in northwestern Missouri. Its northern terminus is at U.S. Route 169 in northwestern De Kalb County; its southern terminus is at US 169 southeast of St. Joseph.
Route 31 was one of the original 1922 state highways. Its northern terminus was originally five miles further north in King City at Route 4. That section of Route 31 became part of U.S. Route 169.