Brigham City is a city in Box Elder County, Utah, United States. The population was 17,899 at the 2010 census. It is the county seat of Box Elder County. It lies on the western slope of the Wellsville Mountains, a branch of the Wasatch Range at the western terminus of Box Elder Canyon. Brigham City saw most of its growth during the 1950s and 1960s, but has seen a struggling economy and stagnating growth since then.