According to the United States Census Bureau, the city has a total area of . All of it is land and none of it is covered by water. Gunnison is near Blue Mesa Reservoir. Primary access to Gunnison is from Salida to the east via Monarch Pass or from Montrose, Colorado to the west via Cerro Summit on U.S. Highway 50. U.S. Highway 50 is the main east-west thoroughfare through the town. There are numerous other ways to get to Gunnison, some of which are subject to seasonal closures (Kebler Pass, Cottonwood Pass). At the 2010 Census there was a population of 15,324 within the county.