Southwest Philadelphia can be described as extending from the western side of the Schuylkill River to the city line, with the SEPTA Media/Elwyn Line serving as the northern border. The northern border is also defined by the Philadelphia City Planning Commission as east from the city line along Baltimore Avenue moving south along 51st Street to Springfield Ave. It follows the train tracks until 49th Street. From 49th and Kingsessing Ave the line moves east along Kingsessing Ave. The line then moves south along 46th St to Paschall Ave where it jogs to join Grays Ferry where the line runs to the Schuylkill River.
Southwest Philadelphia is also described by the city as being the area south of Baltimore Avenue, this definition has historical merit as Baltimore Avenue between 49th and 52nd Streets was known as "The Hub of Southwest Philadelphia" at the turn of the 20th century. Today however the Media/Elwyn tracks are the more common reference dividing Southwest from West Philadelphia.