The Pennsylvania Turnpike was the first modern, limited-access highway in the United States. The dream of a high-speed roadway without railroad crossings or intersecting roads was revolutionary in the 1930s; only the Autobahn in Germany had achieved it. The completed turnpike, today one of sixteen in the nation, cut in half the time it took to travel from the New Jersey coast to the Ohio border. The first section of its 359 miles opened in October 1940 and was touted as the “allweather” road joining Harrisburg and Pittsburgh, with no grade steeper than 3 percent. The route chosen followed the path of the South Pennsylvania Railroad begun fifty years earlier, but halted with several of its tunnels partially bored and a significant portion of its roadway already carved out of Pennsylvania's tree-covered mountains. The turnpike began as a four-lane highway, narrowing to two lanes at each of its seven original tunnels. In the 1960s, three of the tunnels were bypassed, and four were expanded with a parallel tunnel cut into the mountains to ease the traffic congestion. By 1968, the Pennsylvania Turnpike was four lanes of uninterrupted traffic flowing across the state. It passes through eight western Pennsylvania counties: Huntingdon, Fulton, Bedford, Somerset, Westmoreland, Allegheny, Beaver, and Lawrence. Two major bridges over the Beaver and Allegheny rivers and two major tunnels, the Allegheny and Tuscarora, carry the road 180 miles across southwestern Pennsylvania.
Under contract with the Standard Oil Company of Pennsylvania, eleven gas stations and service plazas were built along the first 160 miles of the turnpike between Carlisle and Irwin. The stone-clad buildings, reminiscent of Pennsylvania's classic three- to-five-bay houses, projected a homelike, welcoming appearance with their white-painted shutters and wood-paneled interiors. Howard Johnson's ran the original South Midway restaurant and the other coffee-shop lunch counters, which quickly expanded into full-service restaurants as the road's popularity increased. The two-and-one-half-story Georgian Revival South Midway plaza in Bedford County, which was designed as the flagship facility of the turnpike, retains elements of its original interior features, including two wood-paneled dining rooms; the other plazas have been adapted to fast food companies' requirements.
The final two sections of the turnpike joining the midsection to the borders east and west were completed when Governor James Duff and Richard K. Mellon pushed them through with favorable financing from Mellon Bank. A very low bid submitted for automotive and food services by the Mellon-financed Gulf Oil Company ensured that when both extensions were completed by 1951, Gulf and Howard Johnson's provided the service stations and food.
The buildings associated with the turnpike range from service plazas and maintenance structures to tollbooths and offices. Most of the office structures are buff brick with flat roofs, though there are several red brick maintenance buildings and several remaining stone-faced service plazas. Oddly, the design of the plazas diverged completely from the tollbooths. The original hexagonal tollbooths and their small associated buildings were modern and sleek, completely unlike the residential look associated with the plazas. In 1983, automatic ticket dispensers and redesigned tollbooths were installed, but an original hexagonal tollbooth was donated to the Smithsonian Institution in Washington, D.C.