Greater Portland Metro
| A METRO bus in 2023 | |
| Founded | 1966 | 
|---|---|
| Headquarters | 114 Valley Street, Portland, Maine | 
| Locale | Greater Portland, Maine | 
| Service area | Portland, Brunswick, Gorham, Falmouth, Freeport, South Portland, Westbrook and Yarmouth | 
| Service type | Bus service, express bus service | 
| Routes | 14 | 
| Hubs | 
 | 
| Fleet | 31 | 
| Operator | Greater Portland Transit District | 
| Chief executive | Glenn Fenton (as of July 2024) | 
| Website | Greater Portland METRO | 
The Greater Portland METRO is a regional public transportation system, established in 1966, in Southern Maine. Operated by the Greater Portland Transit District, a transit district comprising Portland, Westbrook, Falmouth, Yarmouth, Freeport, Brunswick, the system also covers downtown Gorham and South Portland.
METRO is Maine's largest public transportation agency. The transit system's annual ridership was 1,850,686 in 2017.
As of 2016, METRO operated a fleet of eighteen compressed natural gas (CNG) buses and fourteen diesel buses. It operates and maintains the only CNG fuel station in the state of Maine.