It operates mostly as a deep-level subway in more densely populated parts of the D.C. metropolitan area (including most of the District itself), while most of the suburban tracks are at surface level or elevated.

[13] In 1966, a bill creating WMATA was passed by the federal government, the District of Columbia, Virginia, and Maryland,[6] with planning power for the system being transferred to it from the NCTA.

[18] Construction began after a groundbreaking ceremony on December 9, 1969, when Secretary of Transportation John A. Volpe, District Mayor Walter Washington, and Maryland Governor Marvin Mandel tossed the first spade of dirt at Judiciary Square.

[19] The first portion of the system opened on March 27, 1976, with 4.6 miles (7.4 km) available on the Red Line with five stations from Rhode Island Avenue to Farragut North, all in Washington, D.C.[20][21] All rides were free that day, with the first train departing the Rhode Island Avenue stop with Metro officials and special guests, and the second with members of the general public.

[31] Metro construction required billions of federal dollars, originally provided by Congress under the authority of the National Capital Transportation Act of 1969.

By 2016, according to The Washington Post, on-time rates had dropped to 84%, and Metro service was frequently disrupted during rush hours because of a combination of equipment, rolling stock, track, and signal malfunctions.

[42][43] In March 2022, Metro announced that beginning on September 10, 2022, it would suspend all service on the Yellow Line for seven to eight months to complete repairs and rebuilding work on its bridge over the Potomac River and its tunnel leading into the station at L'Enfant Plaza.

At that time, Metro announced that it would reduce its service hours from 5:00 a.m. to 9:00 p.m. on weekdays and 8:00 a.m. to 9:00 p.m. on weekends beginning on March 16 to accommodate for train cleaning and additional track work.

WMATA has authorized DVD-rental vending machines and ticket booths for the Old Town Trolley Tours and is seeking additional retail tenants.

[86][37] For Fiscal Year 2019, the estimated farebox recovery ratio (fare revenue divided by operating expenses) was 62 percent, based on the WMATA-approved budget.

[107] The 7000-series railcars, built by Kawasaki Heavy Industries Rolling Stock Company of Kobe, Japan, were delivered for on-site testing during winter 2013–2014, and first entered service on April 14, 2015, on the Blue Line.

This design allows for increased passenger capacity, elimination of redundant equipment, greater energy efficiency, and lower maintenance costs.

The National Transportation Safety Board investigation of the fatal June 22, 2009, accident led it to conclude that the 1000-series cars are unsafe and unable to protect passengers in a crash.

[112][113] While these railcars would have a similar appearance to the 7000-series, the 8000-series would include more features such as "smart doors" that detect obstruction, high-definition security cameras, more space between seats, wider aisles, and non-slip flooring.

Metro began testing reinstating automatic train door opening in March 2019, citing delays and potential human error.

When the Yellow Line reopened on May 7, 2023, following major maintenance work, the Mount Vernon Square turnback was reinstated at all times, which has not happened since 2006.

[134] WMATA temporarily discontinued late night rail service on May 30, 2016, so that Metro can conduct an extensive track rehabilitation program in an effort to improve the system's reliability.

Due to security concerns related to the January 6 United States Capitol attack, several Metro stations were closed for the 2021 Inauguration.

Rush+ had the additional effect of giving some further number of passengers transfer-free journeys, though severely increasing headways for the portion of the Blue Line running between Pentagon and Rosslyn.

[147] WMATA also provides current train and related information to customers with conventional web browsers, as well as users of smartphones and other mobile devices.

Free apps are available to the public on major mobile device software platforms (iOS, Android, Windows Phone, Palm).

[185] On October 27, 2008, the Metro Transit Police Department announced plans to immediately begin random searches of backpacks, purses, and other bags.

On the first day of searches, at least one false positive for explosives was produced, which Metro officials indicated could occur for a variety of reasons including if a passenger had recently been in contact with firearms or been to a firing range.

The National Transportation Safety Board (NTSB) investigation found that the crash was a result of a failure in the train's computer-controlled braking system.

[205] On January 7, 2007, a Green Line train carrying approximately 120 people derailed near the Mount Vernon Square station in downtown Washington.

Workers manually inspect wheels on eight trains daily to catch the defect before it becomes problematic; the remaining cars are out of service pending an automated fix.

[223] On March 14, 2016, an electrified rail caught fire between McPherson Square and Farragut West, causing significant disruptions on the Blue, Orange, and Silver lines.

The need to increase capacity has renewed plans to add 220 cars to the system and reroute trains to alleviate congestion at the busiest stations.

[241] The project was originally envisioned as a circular heavy rail line connecting the outer stations on each branch of the Metrorail system, in a pattern roughly mirroring the Capital Beltway.

[246][247] The District of Columbia Department of Transportation completed construction and began operating a single 2.2 miles (3.5 km) line of the DC Streetcar system in 2016.