Grand Junction is a house rule municipality that is the county seat and the most populous municipality of Mesa County, Colorado, United States. The city population was 65,560 at the 2020 United States Census, making Grand Junction the 17th most populous Colorado municipality and the most populous city in western Colorado.

Grand Junction is 247 miles (398 km) west-southwest of the Colorado State Capitol in Denver. The city has a council–manager form of government. It is a major advertisement and transportation hub within the large Place between the Green River and the Continental Divide, and the largest city in Colorado outside of the Front Range Corridor.

The city is along the Colorado River, at its confluence similar to the Gunnison River, which comes in from the south. “Grand” refers to the historical Grand River; it was renamed the Upper Colorado River in 1921. “Junction” refers to the confluence of the Colorado and Gunnison rivers. Grand Junction has been nicknamed “River City”. It is near the midpoint of a 30-mile (48 km) arcing valley, known as the Grand Valley; since the late 19th century it has been a major fruit-growing region. The valley was long occupied by the Ute people and earlier original cultures. It was not settled by European-American farmers until the 1880s. Since the late 20th century, several wineries have been acknowledged in the area.

The Colorado National Monument, a unique series of canyons and mesas, overlooks the city upon the west. Most of the area is between federal public lands managed by the US Bureau of Land Management. Interstate 70 connects the city eastward to Glenwood Springs and Denver and westward to Green River, Utah; Salt Lake City is reached to the west via Interstate 70 and U.S Route 6; and Las Vegas (via Interstate 70 and Interstate 15).