As for the Metropolitan Area Express (MAX) light rail system operated by TriMet in Portland, Oregon, the Blue Line comprises the first two light rail lines built in the metro area. The Blue Line was not so named until the addition of the MAX Red Line, as the MAX system had only one line beforehand. The MAX Blue line travels from central Gresham through Northeast Portland, the CBD, under the West Hills, and through Beaverton to Hillsboro.

The first segment of the Blue Line (later to be known as "Eastside MAX") was constructed in the early 1980s and opened in 1986. This 25-kilometer segment was built with $178.3 million in federal funds diverted from the defunct Mount Hood Freeway project, as well as state and local funds contributed to the total cost of $214 million (1986 dollars). It runs from the Cleveland Avenue station in downtown Gresham along Burnside to the Gateway Transit Center/NW 99th Avenue. It then continues along Interstate 84 (the Banfield Freeway) to Lloyd Center/NE 11th Avenue, then along NE Holladay Street to the Rose Quarter Transit Center, across the Steel Bridge, and along NW 1st Avenue and SW 1st Avenue in downtown. It then splits onto two streets, with westbound traffic travelling along SW Morrison Street to the Galleria/SW 10th Avenue stop in downtown Portland, and eastbound traffic travelling along SW Yamhill Street from the Library/SW 9th Avenue stop.

The second segment of the Blue Line (originally called "Westside MAX") was constructed in the 1990s and opened in September 1998 (except for the Civic Stadium/PGE Park and Kings Hill/SW Salmon stations, which opened in September 1997). Construction of this 30-kilometer line was delayed by unexpected difficulties boring and blasting the 5-kilometer tunnel under the Vista Ridge; blasting was halted after neighbors on the hill complained of noise and vibrations. Costs in boring and blasting the tunnel contributed to the large $963.5 million cost of the project. The line continues from the original Eastside MAX line along SW Morrison and Yamhill streets to the PGE Park station (formerly Civic Stadium), turns onto SW 18th Avenue and soon onto SW Jefferson Street, and then shortly after enters the tunnel. The tunnel exits alongside US Highway 26 (the Sunset Highway), which the line then travels along to Oregon Highway 217, then through downtown Beaverton, and along an old railroad right-of-way to downtown Hillsboro, where the line runs along SE Washington Street to the Hatfield Government Center.

Stops along the Blue Line, from east to west are:

Includes information from