Marquette County is a county located in the Upper Peninsula of Michigan. As of the 2020 Census, the population was 66,017. The county seat is Marquette. The county is named for Father Marquette, a Jesuit missionary. It was set off in 1843 and organized in 1851. Marquette County is the largest county in land area in Michigan, and the most populous county in the Upper Peninsula of Michigan.
According to the United States Census Bureau, the county has a total area of 3,425 square miles, of which 1,808 square miles is land and 1,616 square miles (47%) is water. It is the largest county in Michigan by land area and fourth-largest by total area.
The Huron Mountains are located in the county. To the north of the county is Lake Superior.