Big Sky is an unincorporated community and census-designated place in Gallatin County and Madison County , in the southwest of the U.S. state of Montana . As of the 2020 United States census , it had a population of 3,591, up from 2,308 in the 2010 census . The primary industry of the area is tourism. Big Sky is located close to Yellowstone National Park along the western edge of Gallatin County and the eastern edge of Madison County, on U.S. Route 191 . It is approximately midway between West Yellowstone and Bozeman , being around 45 miles (72 km) by road from each. This photograph shows a snow-covered sunset view of Lone Mountain , located near Big Sky Resort and about 7 miles (11 km) west of the town center of Big Sky.