The Pennsylvania Turnpike is considered by some to be America's first superhighway. The original 160-mile (257 km) section between Irwin, Pennsylvania and Middlesex, Pennsylvania was built as a toll road on an old railroad right-of-way. It was constructed in 20 months, and opened in 1940. It was the first modern toll road controlled-access highway in the United States constructed for use by all vehicles, although in many respects it was anticipated by the similar parkway system in the New York City metropolitan area, which was open to non-commercial vehicles only. The Pennsylvania Turnpike, in turn, was the model followed by other states that constructed turnpikes after World War II.

Later extensions to Ohio, New Jersey, and Clarks Summit, Pennsylvania in the northeastern part of the state were built to make the Turnpike part of the northeastern toll road system, which, when complete, made it possible to drive from Maine to Chicago, Illinois without stopping at a traffic light. The total Turnpike system, including extensions, is now 528 miles (850 km) long, and carried 162.3 million vehicles in fiscal year 2000-01. Today, the Turnpike is part of the interstate highway system, signed as Interstate 70; Interstate 76; Interstate 276; and Interstate 95 (when a connection between that highway and the Turnpike is built); with Interstate 476 being a Northeastern Extension of the Turnpike.