The Blue Line of the Washington Metro consists of 27 rapid transit stations from Franconia-Springfield to Largo Town Center. It has stations in Fairfax County, Alexandria and Arlington, Virginia, the District of Columbia, and Prince George's County, Maryland. Thirteen of the line's stations are shared with the Orange Line, and another portion is also shared by the Yellow Line; only eight stations are exclusive to the Blue Line.
Blue Line needs 23 trains (Sixteen 6 car trains and seven 4 car trains) to run at peak capacity.
Service on the Blue Line began on July 1, 1977 on eighteen stations between National Airport in Arlington and Stadium-Armory in Washington – the first link of the Metro to Virginia. The line was extended by three stations to Addison Road on November 22, 1980. Service south of National Airport began on June 15, 1991 when Van Dorn Street opened. The original plan for the line was completed when this link was extended to Franconia-Springfield on June 29, 1997. Two new stations in Maryland – Morgan Boulevard and Largo Town Center – opened on December 18, 2004.
The Blue Line was originally planned to follow a slightly different route. The plan would have sent Blue Line trains to Huntington, with Yellow Line trains serving Franconia–Springfield. This was changed due to a shortage of rail cars at the time of the completion of the line to Huntington. Because fewer rail cars were required to operate Yellow Line service than would be required to run Blue Line service out to Huntington – due to the Yellow Line's shorter route – the line designations were switched. Currently, the Blue Line operates to Huntington only on July 4, as part of Metro's special service pattern on that day.
The following stations are along the line, from west to east.
Metro is currently considering rerouting the Blue Line to clear congestion around the Rosslyn station, where the Blue and Orange lines meet. The plan, which is still in the committee stage, calls for some Blue Line trains to continue on the usual route, while others would run the entire Yellow Line route and beyond to Greenbelt.