Delaware County, colloquially referred to as Delco, is a county located in the U.S. state of Pennsylvania. With a population of 562,960, it 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.Its county seat is Media. Until 1850, Chester City 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.HistoryDelaware County lies in the river and bay drainage area named "Delaware" in honor of Thomas West, 3rd Baron De La Warr, Governor of the nearby English colony of Virginia. The land was "discovered" and explored by Henry Hudson in 1609, and over the next several decades it was variously claimed and settled by the Swedes, the Dutch, and the English. Its original human inhabitants were the Lenni-Lenape tribe of American Indians.
