What was the first long-distance, controlled-access highway in the United States?

Seven tunnels built for the South Pennsylvania Railway during the 1880’s lay abandoned, along with the railway itself, for about half a century. When the automobile started gaining popularity, it was noted that car travel through Pennsylvania’s mountains was difficult. In the 1930’s, the Pennsylvania Turnpike was designed to make use of those tunnels.

The original road was 166 miles long. It connected Irwin, a few miles roughly southeast of Pittsburgh, with Carlisle, a few miles roughly southwest of Harrisburg, the state capital. It opened on October 1, 1940.

After the Second World War, the turnpike was extended. In 1950, the road was built east to Valley Forge, adding a Harrisburg interchange. It was also extended west to the Ohio border, linking Pittsburgh as it did. When the Delaware River Bridge was finished in 1956, the turnpike was extended to traverse Pennsylvania from Ohio to New Jersey, a distance of 360 miles.

During the 1960's, three of the original tunnels were bypassed while the other four were expanded by the construction of new “tubes” through the mountains. At that time, the turnpike was four lanes wide along its entire route. The road has been further improved since, with the addition of interchanges and widening of portions of the road to six lanes.

The Pennsylvania Turnpike is credited for leading to the building of similar roads, as well as the Interstate Highway System.