| State: | ME |
| Type: | ME |
| Route: | 91 |
| Map Custom: | yes |
| Length Mi: | 7.83 |
| Length Round: | 2 |
| Length Ref: | [1] |
| Established: | 1949 |
| Direction B: | West |
| Terminus B: | in South Berwick |
| Direction A: | East |
| Terminus A: | in York |
| Counties: | York |
| Previous Type: | ME |
| Previous Route: | 90 |
| Next Type: | ME |
| Next Route: | 92 |
State Route 91 (SR 91) is a short state highway in southwestern Maine. It runs for 7.83miles, connecting the towns of South Berwick and York.
SR 91 begins at an intersection with U.S. Route 1 (US 1) in York. The highway proceeds out of town to the northwest towards South Berwick, just nicking the corner of Eliot along the way. The first 3miles of the route follow the York River towards South Berwick. SR 91 passes under Interstate 95 (the Maine Turnpike) without an interchange, then has its northern terminus at SR 236.