U.S. Route 34 (US 34) is an east–west United States highway that runs for 1,122 miles (1,806 km) from north-central Colorado to the western suburbs of Chicago.

Through Rocky Mountain National Park it is known as the Trail Ridge Road where it reaches an elevation of 12,183 feet (3,713 m), making it one of the highest paved through highways in the United States.

U.S. Route 34 becomes a toll road for a short distance in Colorado, where it passes through Rocky Mountain National Park.

Closure runs roughly from mid-October to Memorial Day weekend in May, and can occur at any time in summer due to high alpine snow storms.

East of Osceola, it continues through Chariton and Georgetown then onto Albia before meeting U.S. Route 63 at a traffic circle in Ottumwa.

In 2015, a 15-mile segment of U.S. Route 34 in Montgomery and Adams counties won the Sheldon G. Hayes Award for the highest quality asphalt pavement in the nation.

It passes through or around the cities of Monmouth, Galesburg, Kewanee, Princeton, Mendota, Yorkville, Oswego, Aurora, Naperville, Lisle, Downers Grove, Westmont, Clarendon Hills, Hinsdale, Western Springs, La Grange, Brookfield, Lyons and Riverside and continues in a largely southwest-northeast direction to its eastern terminus at Illinois Route 43 and Historic US 66 in Berwyn.