State Highway 18 serves as an east–west route between Brainerd, Garrison, Mille Lacs Lake, and Finlayson in east-central Minnesota.

The route passes around the north end of Mille Lacs Lake, which is a popular fishing and recreational destination in Minnesota.

Highway 18 passes through the Wealthwood State Forest in Aitkin County.

Banning State Park is located east of the junction of Highways 18 and 23; opposite the I-35 freeway near Askov and Sandstone.

[3] The section of State Highway 18 between Brainerd and U.S. 169 at Garrison was authorized on November 2, 1920.