Route 23 was established sometime prior to 1877 as the Germantown Avenue Line, and ran from Germantown Depot to 8th and Dauphin streets. In 1890 the line was extended to the 4th and 8th Street trolleys and renamed the Pelham Line. It was combined with the Mermaid and Chestnut Hill Line in 1913, and renamed the Germantown, 10th and 11th Streets Line. The northern terminus was extended to the Bethlehem Pike Loop in 1920, while the southern terminus was extended to 11th Street and Pattison Avenue in 1926, and to 10th Street and Bigler Avenue in 1957. Route 20 service on 13th Street and to Olney Terminal was eliminated with this merge.