Delaware County, with a population of 562,960, is the fifth most populous county in Pennsylvania, and the third smallest in area.
The county was created on September 26, 1789, from part of Chester County and named for the Delaware River. Delaware County is roughly diamond-shaped, with the four sides formed by the Chester County boundary to the northwest, the boundary with the state of Delaware (a portion of the "Twelve Mile Circle") to the southwest, the Delaware River, forming the border with the state of New Jersey to the southeast, and the city of Philadelphia and Montgomery County to the east and northeast. Delaware County is bisected north to south by Blue Route Interstate 476, which connects I-76 just north of the extreme northern corner of the county to I-95, which parallels the Delaware River along the southeastern edge of the county. The area is home to SEPTA's 69th Street Terminal in Upper Darby, and is served by the Norristown High Speed Line, two Red Arrow trolley lines, four Regional Rail Lines and a host of bus routes. Boroughs and townships include Media, Springfield, Swarthmore, Lansdowne, Drexel Hill and Upper Darby.