Grand Junction is a home rule municipality that is the seat of government and largest city of Mesa County, Colorado, United States. Grand Junction's population was 65,560 at the 2020 United States Census, making it the most populous city in western Colorado and the 17th most populous Colorado municipality overall. Grand Junction is a major city along Interstate 70, being the economic and cultural center of Colorado's Western Slope, as well as roughly the halfway point between Denver and Salt Lake City. The city is also a college town, home to Colorado Mesa University.