America's first four-lane limited access highway started at just 160 miles in the coal-rich commonwealth. Now 550 miles long, the Pennsylvania Turnpike celebrated its 75th anniversary on Oct. 1. Nine years over the states' average retirement age, the ever-expanding infrastructure is not planning on slowing down any time soon.

In 2015 E-ZPass exit 87 on Route 903 was added between Mahoning Valley exit 74 and Pocono exit 95 connecting the Northeast Extension Interstate 476 with Route 903 in Penn Forest. Before the E-ZPass-only exit was added, the 20 miles between exits was the longest unbroken stretch without an interchange in the system. The $40 million project was paid for using only toll revenues - testament to how heavy traveled the turnpike truly is.The Pennsylvania turnpike was a large project for America to undertake in the 1940s. The first of its kind, the original route spread between Carlisle of Cumberland County to Irwin in Westmoreland County. Pennsylvania began work on its interstates 16 years earlier than the rest of the country, "Before the big boom," Turnpike spokesman Carl DeFebo said.In the 1950s, 110 more miles were added to the system. A sharp focus on safety in the 1960s led to high concrete medians and setback plazas. Construction and maintenance continued throughout the system over the next 30 years.In 1990s the turnpike saw the first major expansion since 1958. The second Lehigh Tunnel, for southbound traffic, was included in the major expansion project which closed construction on time and under budget. The New Austrian Tunnel Method was used to create the tunnel, a method reserved for railways. Sections of rock in the Blue Mountain were blasted away, the debris cleared, then immediately the top and sides were sprayed with shockcrete. A steel superstructure was then added to the tunnel, DeFebo said.The second tunnel was constructed to help ease traffic congestion caused by the growing popularity of the Poconos. At the time the stretch saw an average of 230,000 vehicles in the month of August.The 2000 decade mile count for the turnpike hit 514 miles, carrying an average of over 156 million vehicles. E-ZPass started to hit popularity after being released to the public.Now up to its current 550-mile range, the 2015 traffic reports an average of 300,000 vehicles daily in the peak month of August. Though construction will always delay travelers the turnpike is clearly the best choice for commuters or the long-distance traveling tourists.