Rum River State Forest, State forest in Mille Lacs County, United States.

Rum River State Forest lies in Kanabec, Mille Lacs and Morrison counties in central Minnesota, along the Rum River just south of Mille Lacs Lake. Upland areas are covered by northern hardwoods such as maple, oak, ash, elm and basswood, while tamarack and black spruce grow in the lowland and marshy areas. The Minnesota Department of Natural Resources manages the forest.

The original forest of white pine, red oak and white oak was logged and floated down the Rum River and Ann River to sawmills downstream. Farms that followed along the river largely failed in the 1930s and were abandoned. In 1935 the Minnesota Legislature established the Rum River and Mille Lacs state forests, and in 1963 the two were combined into Rum River State Forest.

The forest's northern boundary touches Mille Lacs Kathio State Park, where 19 identified archaeological sites make up one of Minnesota's most significant archaeological collections. The Rum River itself carried logs to downstream sawmills, and the river corridor through this area later drew farm settlement.

A trail network runs through the forest accommodating hiking and mountain biking in warm months and cross-country skiing in winter. Visitors should prepare for changing conditions since water and marshland shape the terrain and certain paths vary with the season.

The forest's northern boundary touches Mille Lacs Kathio State Park, where 19 identified archaeological sites make up one of Minnesota's most significant archaeological collections. The park lies just north of the forest, beside Mille Lacs Lake.