Sault Ste. Marie, officially the City of Sault Sainte Marie, is a city in, and the county seat of, Chippewa County in the U.S. state of Michigan. It is on the northeastern end of Michigan's Upper Peninsula, on the Canada–US border, and separated from its twin city of Sault Ste. Marie, Ontario, by the St. Marys River. The city is relatively isolated from other communities in Michigan and is 346 miles via I-75 from downtown Detroit. The population was 14,144 at the 2010 census, making it the second-most populous city in the Upper Peninsula. By contrast, the Canadian Sault Ste. Marie is much larger, with more than 75,000 residents, based on more extensive industry developed in the 20th century and an economy with closer connections to other communities.