Interstate 80
I-80 is the Interstate Highway that most closely approximates the route of the historic Lincoln Highway, the first road across the United States. The highway roughly traces other historically significant travel routes in the Western United States: the Oregon Trail across Wyoming and Nebraska, the California Trail across most of Nevada and California, the first transcontinental airmail route, and except in the Great Salt Lake area, the entire route of the First Transcontinental Railroad. From near Chicago east to near Youngstown, Ohio, I-80 is a toll road, containing the majority of both the Indiana Toll Road and the Ohio Turnpike. I-80 runs concurrently with I-90 from near Portage, Indiana, to Elyria, Ohio. In Pennsylvania, I-80 is known as the Keystone Shortway, a non-tolled freeway that crosses rural north-central portions of the state on the way to New Jersey and New York City.
Pan-American Highway
In 1966, the Federal Highway Administration designated the entire Interstate Highway System part of the Pan-American Highway System, although this has never been reflected in any of the official interstate signage. Of the many freeways that make up this very comprehensive system, there are several that stand out because of their mainly north-south orientation and their links to the main Mexican route and its spurs as well as to key routes in Canada that link to the Alaska Highway. These include the following:Several North American routes have names that make no direct reference to the Pan-American Highway, in part because some sections follow highways that are not up to full freeway standardThe official route of the Pan-American Highway through Mexico (where it is known as the Inter-American Highway) starts at Nuevo Laredo, Tamaulipas (opposite Laredo, Texas) and goes south to Mexico City along Mexican Federal Highway 85. Later branches were built to the border as follows: