Pennsylvania Turnpike

(Wikipedia) ... When the Pennsylvania Turnpike opened in 1940, it was the first long-distance rural highway in the United States and was popularly known as the "tunnel highway" because of the seven mountain tunnels along its route.
The turnpike was partially constructed on an unused railroad grade constructed for the aborted South Pennsylvania Railroad project, and six of its seven original tunnels (all tunnels with the exception of the Allegheny Mountain tunnel) were first bored for that railroad.
Proposals to use the grade and tunnels for a toll road were made starting in late 1934. The road would bypass the steep grades on Pennsylvania's existing major east-west highways – US 22 (William Penn Highway) and US 30 (Lincoln Highway) – and offer a high-speed four lane route free of cross traffic. Continued 

Photo: Library of Congress