State Highway 78 serves as a north–south route in west-central Minnesota between Erdahl, Ashby, Battle Lake, Ottertail, and Perham.

Glendalough State Park is located 1.8 mile east of the junction of Highway 78 and County Road 16 near Battle Lake.

The park entrance is located on County Road 16.

Minnesota DNR website for Glendalough State Park - Link

In exchange, Minnesota State Highway 54 was turned back to Grant County, and is now CSAH 54.