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, and Brunswick,^[1] the system also covers Gorham and The Maine Mall portion of South Portland.

METRO is Maine's largest public transportation agency. The transit system's annual ridership was 1,850,686 in 2017.^[2]

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.

The ancestor to the METRO, the Portland and Forest Avenue Railroad Co., began operating horse-drawn lines in 1860. They were upgraded to streetcars in 1891, which operated for fifty years before the company switched to buses. The company's new parent, Central Maine Power, sold the buses to Portland Coach Company in 1944.

Concerned about the viability of transit in the region, the Greater Portland Transit District was created in 1966. Three years later it purchased the struggling Portland Coach Company, which became METRO in 1976. Several municipalities serviced by METRO withdrew during an age of contraction; service to Yarmouth and Cape Elizabeth ended in 1978, South Portland withdrew in 1983 (although METRO continues to run select buses to the city), and the Portland School Department began operating its own buses in 1985.

The system began to turnaround in the late 1990s, and in 2004 it expanded to Falmouth, which later joined the Greater Portland Transit District. Portland Public Schools ended yellow school bus transportation for all of Portland's high school students and entered into an agreement with METRO to provide each student with a free unlimited METRO pass starting in 2015.^[3] The program has generated 250,000 boardings for the agency while allowing Portland Public Schools greater flexibility with school bell times and repurposing staff and equipment resources to other priorities. Portland charter school Baxter Academy for Technology and Science also offers METRO passes to students.^[4]

The METRO BREEZ express service started in June 2016. It serves Portland, Falmouth, Yarmouth, Freeport and Brunswick. Two new lines debuted in August 2018 serving Gorham and adding expanded service to Westbrook.^[5] New buses with USB ports and Wi-Fi were introduced around 2020,^[6] as were bus shelters.^[7]

METRO operates two hubs, one in downtown Portland called the METRO Pulse and one in downtown Westbrook called the Westbrook Hub. Additionally, the Portland Transportation Center, which provides an intercity bus connection and Amtrak service, serves as a major transfer point.

Intercity service from York County connects to the METRO system at The Maine Mall and at several stops along Congress Street.^[8] The South Portland Bus Service also connects to METRO at these locations.^[9]

Local routes are numbered 1 through 9, with the 9 split into 9A and 9B. There is currently no route 6. There is one lettered route, the Husky Line (H), which connects the Gorham and Portland campuses of the University of Southern Maine.^[10] There is one express route, the BREEZ, which runs between Portland and Brunswick; on signage, it is identified as "B".

• Public transportation in Maine