Delaware County, Pennsylvania
County in Pennsylvania, United States Delaware County , Pennsylvania County of Pennsylvania County of Delaware, Pennsylvania A collage of notable places in Delaware County Flag Seal Location within the U.S. state of Pennsylvania Pennsylvania's location within the U.S. Founded September 26, 1789 Named for Delaware River Seat Media Largest city Chester Area • Total 191 sq mi (495 km 2 ) • Land 184 sq mi (477 km 2 ) • Water 6.8 sq mi (18 km 2 ), 3.5% Population (est.) • (2017) 564,696 • Density 3,065/sq mi (1,183/km 2 ) Congressional district 5th Website www.co.delaware.pa.us Footnotes: Pennsylvania Historical Marker Designated October 3, 1982 [1] Interactive map of Delaware County, Pennsylvania Delaware County , colloquially referred to as Delco , [2] is a county located in the U.S. state of Pennsylvania. With a population of 562,960, [3] it is the fifth most populous county in