The Pennsylvania Avenue Limited Line, designated Route 39 was a limited weekday peak-hour only MetroExtra route that operated between Naylor Road station of the Green Line of the Washington Metro and Potomac Park.

Route 39 originally operated as the Friendship Heights-Van Ness-UDC Line and operated between Friendship Heights station and Van Ness-UDC station.

[2] On December 15, 2019, the route was to travel across the National Mall along 4th Street between Pennsylvania Avenue NW and Independence Avenue SW to improve safety and provide more direct service.

[3] In response to the COVID-19 Pandemic, WMATA suspended all 39 service on March 16, 2020.

[4] During the suspension, WMATA proposed to eliminate Route 39 on their FY2021 budget.