Interstate 80 (abbreviated I-80) is the second-longest Interstate Highway in the United States (after I-90). It connects downtown San Francisco, California to Teaneck, New Jersey, a suburb of New York City, just as the Lincoln Highway did in the years before the Interstate Highway System. The highway roughly traces some historically significant travel corridors, particularly in the Western U.S. These include the Oregon Trail in Nebraska and westward, the California Trail in Nevada and California, and the Transcontinental Railroad from western Nebraska to San Francisco.

The highway from near Chicago, Illinois, east to near Youngstown, Ohio, is a toll road - the ticketed portion of the Indiana Toll Road and the majority of the Ohio Turnpike. At Youngstown I-80 leaves the tolled alignment, which continues toward Pittsburgh and Philadelphia, in favor of the Keystone Shortway, a shortcut across northern Pennsylvania built as part of a new corridor for I-80. The tolled route to Philadelphia, Pennsylvania was originally designated Interstate 80S, and is now Interstate 76.

I-80 intersects I-90 near Elyria, Ohio, and they share a route west all the way to Portage, Indiana, where I-90 splits off but I-80 then runs concurrently with I-94 until the Chicago suburb of South Holland, Illinois. I-80 then runs concurrently with I-294 until Markham, Illinois. It is one of the most heavily traveled trans-continental interstates.

I-80 map