U.S. Route 6

U.S. Route 6
Grand Army of the Republic Highway
US 6 highlighted in red
Route information
Length	3,198.87 mi (5,148.08 km)
Existed	1926–present
Major junctions
West end	US 395 in Bishop, CA
Major intersections	I-15 in Spanish Fork, UT I-70 near Green River, UT I-25 in Denver, CO I-35 / I-80 in Clive, IA I-55 in Channahon, IL I-80 / I-94 between South Holland, IL, and Lake Station, IN I-65 in Gary, IN I-75 in Bowling Green, OH I-90 in Cleveland, OH I-95 in Providence, RI
East end	Route 6A in Provincetown, MA
Location
Country	United States
States	California, Nevada, Utah, Colorado, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, New York, Connecticut, Rhode Island, Massachusetts
Highway system
United States Numbered Highway System List Special Divided
← US 5 US → US 7 ← Route 2A N.E. → Route 4

U.S. Route 6 (US 6) or U.S. Highway 6 (US 6), also called the Grand Army of the Republic Highway, honoring the American Civil War veterans association, is a main route of the United States Numbered Highway System. While it currently runs east-northeast from Bishop, California, to Provincetown, Massachusetts, the route has been modified several times. The highway's longest-lasting routing, from 1936 to 1964, had its western terminus at Long Beach, California. During this time, US 6 was the longest highway in the country.

In 1964, the state of California renumbered its highways, and most of the route within California was transferred to other highways. This dropped the highway's length below that of US 20, making it the second-longest U.S. Route in the country. However, since US 20 has a discontinuity through Yellowstone National Park, US 6 remains the longest continuous U.S. Route in the country.

US 6 is a diagonal route, whose number is out of sequence with the rest of the U.S. Route grid in the Western U.S. When it was designated in 1926, US 6 only ran east of Erie, Pennsylvania. Subsequent extensions, largely replacing the former U.S. Route 32 and U.S. Route 38 (US 38), have taken it south of US 30 at Joliet, Illinois, US 40 near Denver, Colorado (past the end of US 38), US 50 at Ely, Nevada, and US 70 near Los Angeles, California, due to its north–south alignment in that state.

US 6 does not serve a major transcontinental corridor, unlike other highways. George R. Stewart, author of U.S. 40: Cross Section of the United States of America, initially considered US 6, but realized that "Route 6 runs uncertainly from nowhere to nowhere, scarcely to be followed from one end to the other, except by some devoted eccentric".