Pennsylvania Route 100 is a 59.4-mile (95.6 km) long state highway in the U.S. state of Pennsylvania that runs from U.S. Route 202 near West Chester north to PA 309 in Pleasant Corners. The route runs between the western suburbs of Philadelphia and the Lehigh Valley region of the state, serving Chester, Montgomery, Berks, and Lehigh counties. PA 100 intersects several important highways, including US 30 in Exton, the Pennsylvania Turnpike (Interstate 76, near Lionville, US 422 near Pottstown, US 222 in Trexlertown, and I-78/US 22 in Fogelsville. Several sections of PA 100 are multi-lane divided highway with some interchanges, including between US 202 and the Pennsylvania Turnpike in Chester County between south of Pottstown and New Berlinville, and between Trexlertown and Fogelsville.

U.S. Route 202 is a US Highway running from New Castle, Delaware, northeast to Bangor, Maine. In the U.S. state of Pennsylvania, the route runs for 59 miles (95 km), from the Delaware state line in Bethel Township, Delaware County, to the New Hope–Lambertville Toll Bridge over the Delaware River in Solebury Township, where the route crosses into New Jersey. The highway runs through the western and northern suburbs of Philadelphia in the Delaware Valley metropolitan area, and serves as a toll-free bypass around the city, avoiding the busy traffic and congestion on Interstate 95 (I-95). It is signed north–south and follows a general southwest–northeast direction through the state.