Brigham City is a city in Box Elder County, Utah, United States. The population was 19,650 at the 2020 census, up from the 2010 figure of 17,899. 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. It is near the former headquarters of ATK Thiokol, now Northrop Grumman, the company that created the solid rocket boosters for the Space Shuttle.