A WESA listener’s question about Pennsylvania Turnpike mile markers launches a retrospective on the highway’s origins in Depression-era America, it’s design and construction challenges, and the role the federal government played in financing. The article notes, “Nowadays, the turnpike may feel like any other roadway, but its then-modern design and innovative approach to vehicular travel give it a special place in American infrastructure history.” Once called the “World’s Greatest Highway,” the turnpike “helped lay the foundation for what would become the federal interstate highway system.”