Chester County, colloquially referred to as Chesco, is a county in the Commonwealth of Pennsylvania. It is located in the Delaware Valley region, located in the southeastern part of the state. As of the 2020 census, the population was 545,823. increasing by 7.1% from 498,886 in 2010. The county seat is West Chester. The most populous of the county's 73 municipalities, including cities, boroughs, and townships,<!--https://dced.pa.gov/local-government/municipal-statistics/municipalities/ shows that the State of PA classifies boroughs, townships, and cities as types of municipalities-->) is Tredyffrin Township. The most populous boroughs are West Chester and Phoenixville. Coatesville is the only municipality in the county that is classified as a city. The county is part of the Philadelphia metropolitan area.
Chester County was one of the three original Pennsylvania counties created by William Penn in 1682. It was named for Chester, England. It is part of the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD metropolitan statistical area. Along with northern Delaware County and southern Montgomery County, eastern Chester County is home to many communities that comprise part of the Philadelphia Main Line western suburbs of Philadelphia.
As of 2020, the county had the highest median household income level in Pennsylvania, and the 35th-highest in the nation.
History
thumb|A historic marker describing Chester County
Philadelphia, Bucks, and Chester were the three counties created by William Penn on August 24, 1682, in the colonial-era Province of Pennsylvania.
At the time, Chester County's borders were Philadelphia County to the north, the ill-defined western edge of the colony, located approximately at the Susquehanna River to the west, the Delaware River to the east, and Delaware and Maryland to the south. Chester County replaced the Pennsylvania portion of New Netherland's upland in New York, which was officially eliminated when Pennsylvania was chartered on March 4, 1681, and ceased existing in June of that year. Much of the Welsh Tract was in eastern Chester County, and Welsh place names, given by early settlers, continue to predominate there.
The fourth county in the state, Lancaster County, was formed from Chester County on May 10, 1729. On March 11, 1752, Berks County was formed from the northern section of Chester County and parts of Lancaster and Philadelphia counties.
The southern border of Chester County is the Mason-Dixon Line, surveyed in 1765. An error in surveying resulted in the Wedge, extending south of the line. Chester County claimed the Wedge until 1921, when it was ceded to Delaware.
The original Chester County seat was the City of Chester, a center of naval shipbuilding, at the eastern edge of the county. In an effort to accommodate the increased population of the western part of the county, the county seat was moved to a more central location in 1788; in order to mollify the eastern portion of the county, the village, known as Turk's Head, was renamed West Chester. In response to the new location of the county seat, the eastern portion of the county separated and formed the new Delaware County in 1789 with the City of Chester as its county seat.
Much of the history of Chester County arises from its location between Philadelphia and the Susquehanna River. The first "road to the West," a reference to Lancaster County, passed through the central part of Chester County, following the Great Valley westward; with some realignments, it became the Lincoln Highway and later U.S. Route 30. This road is still named Lancaster Avenue in most of the Chester County towns it runs through. The first railroad, which became the Pennsylvania Railroad, followed much the same route, and the Reading Railroad progressed up the Schuylkill River to Reading. Industry tended to concentrate along the rail lines. Easy transportation allowed workers to commute to urban jobs, and the rise of the suburbs followed. To this day, the county's developed areas extend along major lines of transportation.
During the American Revolutionary War, the Battle of Brandywine was fought in the southeastern part of the county. The Battle of the Clouds and the Battle of Paoli both took place in the northeastern part of the county, along with George Washington's encampment at Valley Forge.
Geography
According to the U.S. Census Bureau, the county has a total area of , of which is land and (1.1%) is water. The topography consists of rolling hills and valleys and it is part of the region known as the Piedmont.
Watersheds that serve Chester County include the Octoraro, Brandywine, and Chester creeks, and the Schuylkill River. Many of the soils are fertile, rich loam as much as twenty-four inches thick; together with the temperate climate, this was long a major agricultural area. Because of its proximity to Philadelphia, Chester County has seen large waves of development over the past half-century due to suburbanization. Although development in Chester County has increased, agriculture is still a major part of the county's economy, and the number of horse farms is increasing in the county. Mushroom growing is a specialty in the southern portion of the county.
Chester County is the only county to border both Delaware and Maryland.
Elevations (in feet):
High point—1020 Welsh Mt., Honeybrook Twp. Other high points—960 Thomas Hill, Warwick Twp; 960 Barren Hill, West Caln Twp. Low point—66 Schuylkill River, Chester-Montgomery county line. Cities and boroughs: Coatesville 314; Downingtown 255; Kennett Square 300; Oxford 535; Parkesburg 542; Phoenixville 127; Spring City 114; West Chester 459.
Adjacent counties
- Berks County (north)
- Montgomery County (northeast)
- Delaware County (east)
- New Castle County, Delaware (southeast)
- Cecil County, Maryland (south)
- Lancaster County (west)
National protected area
- Valley Forge National Historical Park (part)
State protected areas
- French Creek State Park
- Marsh Creek State Park
- White Clay Creek Preserve
Major roads and highways
thumb|right|[[Interstate 76 in Pennsylvania|I-76/Pennsylvania Turnpike westbound in Chester County]]
Economy and environment
Lanchester Landfill, located on the border of Chester and Lancaster Counties, captures methane which is sold for renewable natural gas credits, and piped to seven local businesses. This reduces the county's methane emissions, and provides an alternative to fracking for shale gas. In addition, several companies have their headquarters or a major presence in the county including Bentley Systems, EBS Healthcare, Main Line Health, Lavazza North America (formerly Mars Drinks), Depuy Synthes (part of Johnson & Johnson), Metabo, QVC, Hankin Group, Axalta Coating Systems, CTDI, Pactiv, Ricoh Americas, Blinding Edge Pictures, J.G. Wentworth, The Vanguard Group, and Victory Brewing Company among others.