Chester County is located west of Philadelphia, with the eastern part of the county consisting of areas of the Philly suburbs Main Line. West Chester is the county seat and is home to West Chester University, one of the state’s most popular colleges. Chester County is one of the three original counties established by William Penn in 1682, at that time the county consisted of all of Chester and Delaware counties. Chester County also has deep roots in the forming of the United States. Valley Forge National Historical Park preserves and protects the location of George Washington’s encampment after British forces seized Philadelphia during the Revolutionary War.