The South Capital Street Limited Line, designated Route W9, was a bus route operated by the Washington Metropolitan Area Transit Authority between L'Enfant Plaza station of the Blue, Yellow, Orange, Green, and Silver lines of the Washington Metro and the Douglas A. Munro Coast Guard Headquarters Building (Coast Guard) or Livingston (AM Peak only).

The line operated during the weekday peak-hours only providing service from the Coast Guard Headquarters to L'Enfant Plaza.

The line was discontinued on June 24, 2018 due to low ridership and the U.S. Coast Guard ending their subsidy for the W9 on July 1, 2018.

Ridership on the W9 decreased as of a result as the shuttle provides access to inside the facility unlike the W9 which can only go as far as the Navy and Air Force Gates.

[5] After construction of the Coast Guard Headquarters completed in 2013, WMATA implemented a new MetroExtra route W9 under the South Capital Street Limited Line.

On March 22, 2018, the United States Coast Guard and WMATA began its talk for a renewed contract.

The new service levels result in a revenue reduction from the Coast Guard, and a minimal expense impact to the operating budget due to the non-revenue trips associated with the A9.

Key highlights include:[5] At the time of the proposal, route W9 has been suffering from low ridership averaging 242 riders out of the expected 432.