Delaware County, colloquially referred to as Delco, is a county located in the state of Pennsylvania. With a 2010 census population of
558,979, it is the fifth most populous county in Pennsylvania, and the third most compact. Its county seat is Media. The county was created on
September 26, 1789, from part of Chester County and named for the Delaware River. Chester City, prior to 1851, was the county seat of both
Delaware County and, before that, of Chester County.
Delaware County is adjacent to the city-county of Philadelphia and is included in the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD Metropolitan
Statistical Area. Delaware County is the only county covered in its entirety by area codes 610 and 484.
Named for the Delaware River, which in turn had been named for Lord de la Warr, governor of Virginia. Media
County QuickFacts: CensusBureau Quick Facts
Created on September 6, 1789, from
part of Chester County, and named for the Delaware River, which in turn had been
named for Lord de la Warr, governor of Virginia. Media, its county seat since
1850, was incorporated as a borough on March 11, 1850, and named for its central
location in the county. Chester, its original county seat, was the county seat
of Chester County before 1788, and the temporary capital of Pennsylvania,
1681-1682, before Philadelphia was laid out. The county adopted a home rule
charter in May 1975.
Delaware includes the first permanent European settlement, the Swedes on Tinicum
Island in 1643. The center of the Battle of Brandywine in 1777 was in Delaware.
Phenomenal population growth occurred steadily after 1800, until a fall off
began in 1980. Its many fast streams made it a milling center for lumber,
grains, paper, tobacco, and textiles, and it was located on main roads south and
west from Philadelphia. Shipbuilding flourished, beginning in the colonial
period, and oil refineries arose in the early twentieth century. Industrial jobs
brought in a large immigrant population and from 1885 to 1915 middle class
families from Philadelphia relocated here. Once a strong dairy and mushroom farm
area, agriculture is now almost gone. Farms occupy only 7 percent of the land.
There were Underground Railroad stations in Chester Borough, Upper Darby, and
Newtown Square, and Martin Luther King Jr. was educated at Crozier Baptist
Seminary. Colleges and universities include Swarthmore, Haverford, Villanova,
Cheyney State, and Widener.
Delaware County is roughly diamond- or kite-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.
As reported by the Census Bureau, the county has a total area of 191 square miles (494 km2), of which, 184 square
miles (477 km2) of it is land and 7 square miles (17 km2) of it (3.42%) is water.
Bordering counties are as follows:
Chester Upland School District
Chichester School District
Garnet Valley School District
Haverford Township School District
Interboro School District
Marple Newtown School District
Penn-Delco School District
Radnor Township School District
Ridley School District
Rose Tree Media School District
Southeast Delco School District
Springfield School District
Upper Darby School District
Unionville-Chadds Ford School District
Wallingford-Swarthmore School District
West Chester Area School District
William Penn School District
Delaware County Technical High School, Aston