Fort Collins is a home rule municipality that is the county seat and the most populous municipality of Larimer County, Colorado, United States. The city population was 169,810 at the 2020 census, an increase of 17.94% since 2010. Fort Collins is the principal city of the Fort Collins, CO Metropolitan Statistical Area and is a major city of the Front Range Urban Corridor. The city is the fourth most populous city in Colorado. Situated on the Cache La Poudre River along the Colorado Front Range, Fort Collins is located 56 mi (90 km) north of the Colorado State Capitol in Denver. Fort Collins is a midsize college town, home to Colorado State University and Front Range Community College's Larimer campus.

Larimer County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 359,066. The county seat and most populous city is Fort Collins. The county was named for William Larimer, Jr., the founder of Denver.