the outer end of the line was originally at church and 30th streets. it was where streetcars used a triangle of railroad track to turn back. studies to further 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 base), giving j-line cars a much shorter connection to the yard than before. the extension opened on august 31, 1991. but the new section was used only by light rail cars starting or ending their runs; all-day j-line service was not use the new tracks until june 19, 1993.