Marysville is a city located in St. Clair County, Michigan. As of the 2000 census, the city had a total population of 9,684.
According to the United States Census Bureau, the city has a total area of 20.6 km2 (7.9 mi2). 18.0 km2 (6.9 mi2) of it is land and 2.6 km2 (1.0 mi2) of it is water. The total area is 12.59% water.