The Pennsylvania Turnpike was planned in the 1930s to make traveling by car better across the mountains of Pennsylvania. It went through seven tunnels that were created for the abandoned South Pennsylvania Railroad in the 1880s. The road opened on October 1, 1940 between Irwin and Carlisle as the first long-distance limited-access highway in the United States that led to the building of other limited-access toll roads and the Interstate Highway System. Following World War II, the turnpike was built east to Valley Forge in 1950 and west to the Ohio border in 1951. In 1954, the road was built east to the Delaware River. The mainline turnpike was done in 1956 when the Delaware River bridge was built. In the 1960s, another tube was bored at four of the two-lane tunnels while the other three tunnels were closed when a new road was built around them. This made all of the highway four lanes wide. Work continues to be done to make the road better, such as rebuilding the original section to today's standards, widening parts of the turnpike to six lanes, and adding new interchanges.