Planning for Metro began with the Mass Transportation Survey in 1955, which attempted to forecast freeway and mass transit systems sufficient to meet the region's needs projected for 1980. In 1959, the study's final report included two rapid transit lines that anticipated downtown Washington subways. Because the plan called for extensive freeway construction within the District of Columbia, alarmed residents lobbied for federal legislation creating a regional transportation agency with a moratorium on freeway construction through July 1, 1962. The new agency, the National Capital Transportation Administration, issued a 1962
Transportation in the National Capital Region report, which did not include the route that became the Yellow Line. A central route under 7th Street in downtown was only added in 1967 primarily to serve the "inner city". In March 1968, the
Washington Metropolitan Area Transit Authority (WMATA) board approved its Adopted Regional System (ARS), which included the Yellow Line from Franconia and Backlick Road (in Springfield) to Greenbelt. While a cut-and-fill tunnel for Yellow Line was built under 7th Street and U Street, street traffic and pedestrian access were difficult. The result was the loss of the traditional retail businesses along the route. The downtown segment of the line was originally projected to open in September 1977. Obtaining approval of the District of Columbia and Prince George's County of the exact alignment of the Yellow Line north of U Street delayed construction. Originally, the ARS called for the line to be placed in the median strip of the planned North Central Freeway,. Service on the Yellow Line began on April 30, 1983, adding to the system and linking the two already-built stations of and with a bridge across the Potomac River. It was extended beyond by four stations to on December 17, 1983, the first station outside the
Capital Beltway. When the
Green Line link to opened on May 11, 1991, it acted as an extension of the Yellow Line until the southern Green Line branch was completed. From 1999 to 2008, the Yellow Line operated to Franconia–Springfield on July 4, as part of Metro's special service pattern on that day. On November 16, 1995, WMATA and the developer of the
Potomac Yard area of Alexandria, Virginia, signed an agreement to construct
Potomac Yard station between Braddock Road and National Airport.
21st century In 2006, Metro board member
Jim Graham and Washington, D.C. Mayor
Anthony A. Williams proposed re-extending Yellow Line service to or even . Their proposal did not involve constructing any new track because either extension would run along the same route as the existing
Green Line, thus relieving crowding on that line and would require fewer switches to maintain making operations easier. Suburban members of the board initially resisted the proposal. Through a compromise that also increased service on the
Red Line, on April 20, 2006, the WMATA board approved a Yellow Line extension to the Fort Totten station during off-peak hours. An 18-month pilot program began on December 31, 2006, at a cost of $5.75 million to the District of Columbia. On June 26, 2008, due to the success of the 18-month trial, the Yellow Line was permanently extended to Fort Totten at all times except peak hours. To accommodate platform reconstructions, the Blue and Yellow Lines south of Ronald Reagan Washington National Airport were closed from May 25 to September 8, 2019, in the longest line closure in Metro's history. The Yellow Line was extended to Greenbelt at the beginning of the closure and retained after. On May 7, 2023, Yellow Line trains were shortened to Mount Vernon Square at all times being replaced by additional Green Line trains. All stations were reopened beginning on June 28, 2020. Between February 13 and May 13, 2021, additional Yellow Line trains began operating between Mount Vernon Square and at all times, replacing the
Blue Line due to it being suspended because of platform reconstruction at and . Between May 29 and September 6, 2021, all Yellow Line trains terminated at Mount Vernon Square due to a platform improvement project which closed stations north of . Yellow Line trains were suspended beginning September 10, 2022, to tie in
Potomac Yard station and to rehabilitate the
14th Street Bridge that the Yellow Line operates over. Service was replaced by additional Green Line trains, as well as Blue Line trains that operated between and stations. The Yellow Line reopened on May 7, 2023, with its northeastern terminus cut back from Greenbelt to Mount Vernon Square. Potomac Yard station opened on May 19, 2023.
Automatic train operation on the Yellow and Green lines, which had ceased following the
2009 Red Line train collision, was allowed to resume in May 2025. Effective December 31, 2025, half of all Yellow Line trains have been re-extended to Greenbelt. == Route ==