Chester County, Pennsylvania, USA
County or equivalent
Location overview
Chester County lies west of Philadelphia in southeastern Pennsylvania, with West Chester as its county seat. Rolling farmland, wooded ridges and the valleys of Brandywine Creek and the Schuylkill River give the county a varied landscape within the Piedmont. Established in 1682 as one of Pennsylvania’s three original counties, it preserves sites associated with colonial settlement, ironmaking and the Revolutionary War. Chester County had about 557,100 residents in 2025. Agriculture, including its nationally prominent mushroom industry, remains visible alongside life sciences, technology, health care, education, manufacturing and professional services.