Great Falls is a city in and the county seat of Cascade County, Montana, United States. The 2015 census estimate put the population at 59,638. The population was 58,505 at the 2010 census. It is the principal city of the Great Falls, Montana Metropolitan Statistical Area, which encompasses all of Cascade County and has a population of 82,278. Great Falls was the largest city in Montana from 1950 to 1970, when Billings surpassed it.