Coatesville is a city in Chester County, Pennsylvania, United States. The population was 13,350 at the 2020 census. Coatesville is approximately 39 miles west of Philadelphia. It developed along the Philadelphia and Lancaster Turnpike beginning in the late 18th century. It spans U.S. Route 30, the "Main Line" highway that runs west of Philadelphia.

The Philadelphia and Lancaster Turnpike, first used in 1795, is the first long-distance paved road built in the United States, according to engineered plans and specifications. It links Lancaster, Pennsylvania, and Philadelphia at 34th Street, stretching for sixty-two miles. It was later extended by the Lancaster and Susquehanna Turnpike to the Susquehanna River in Columbia. The route is designated Pennsylvania Route 462 from the western terminus to US 30, where that route takes over for the majority of the route. The US 30 designation ends at Girard Avenue in the Parkside neighborhood of Philadelphia, where State Route 3012 takes it from there to Belmont Avenue. At Belmont Avenue, State Route 3005 gets the designation from Belmont Avenue until the current terminus at 34th Street. Historically, Lancaster Pike terminated at Market Street before Drexel University took over the stretch between 32nd and 34th Streets.