Sault Ste. Marie is a city in the Upper Peninsula of the U.S. state of Michigan. It is the county seat of Chippewa County and is the only city within the county. With a population of 13,337 at the 2020 census, it is the second-most populated city in the Upper Peninsula, behind Marquette. It is the primary city of the Sault Ste. Marie, MI Micropolitan Statistical Area, which encompasses all of Chippewa County and had a population of 36,785 at the 2020 census. Sault Ste.