Example image of eyePlorer eyePlorer map for 'Chester County, Pennsylvania': County (United States) Pennsylvania U.S. state County seat West Chester, Pennsylvania Highest-income counties in the United States William Penn Cheshire England Delaware Valley Philadelphia Bucks County, Pennsylvania Philadelphia County, Pennsylvania Delaware Delaware River Maryland Susquehanna River New Netherland New York Welsh Tract 1729 Lancaster County, Pennsylvania May 10 1752 Berks County, Pennsylvania March 11 Chester, Pennsylvania 1789 Delaware County, Pennsylvania September 26 Lincoln Highway U.S. Route 30 Main Line of Public Works Pennsylvania Railroad Reading Company Schuylkill River Battle of Brandywine Valley Forge Valley Forge General Hospital World War II United States Census Bureau Piedmont (United States) Brandywine Creek (Christina River) Chester Creek Octoraro Creek Cecil County, Maryland Census New Castle County, Delaware Valley Forge National Historical Park Population density