all service routed there after January 1, 1941. As part of the creation of the Muni Metro system, it was partially converted to modern light rail operation in 1981 — the last line to do so. While many streetcar lines were converted to bus lines after World War II, the J Church avoided this due to the private right-of-way it uses to climb the steepest grades on Church Street, between 18th Street and 22nd Street. Extension to Balboa Park The outer end of the line was originally at Church and 30th Streets, where streetcars used a wye to turn around. Studies to extend the line from its southern terminus had been made in the 1920s and 1970's. In 1990–91, the tracks were extended to the Balboa Park BART station and the Metro Center (Muni light-rail maintenance and operations base), giving J-line cars a much shorter connection to the yard than previously. The extension opened on August 31, 1991, but the new section was initially used only by light rail cars starting or ending their runs; all-day J-line service was not extended along the new tracks until June 19, 1993. This trackage was laid along the Bernal Cut, the former right-of-way of the San Francisco & San Jose Railroad. This extension of the J-line to the Metro Center now also provides vintage F Market cars a connection to the adjacent Cameron Beach Yard, where they are stored when not in service. Occasionally J-Church streetcars use the siding at 30th and Church as a terminus during rush hours, or during irregular operations. The 19th Avenue Platform & Trackway Improvement Project originally included pocket tracks to allow J Church trains to continue past Balboa Park with service to Stonestown. Due to community backlash, the compromise plan did not include the facilities necessary to run joint J-M service. Later changes The line was temporarily through-routed with the surface section of the K Ingleside line from June 25 to August 24, 2018, due to the Twin Peaks Tunnel shutdown. Service modifications during COVID-19 On March 30, 2020, Muni Metro service was replaced with buses due to the COVID-19 pandemic. Rail service returned on August 22, 2020, with the routes reconfigured to improve reliability in the subway. J Church service ran only on the surface. The J terminated at the inbound platform on Church Street at Market Street, requiring passengers to transfer between the J and