Old Mill State Park in northwestern Minnesota occupies an ancient beach of glacial Lake Agassiz along the Middle River between Argyle and Newfolden. Established from the Larson family homestead begun in 1882, the site developed through a series of river-powered and wind-powered mills before a steam mill took over. Acquired by the state in 1937, it preserves the rebuilt Larson Mill, still run for special demonstrations, along with a 25-acre historic district of Works Progress Administration buildings listed on the National Register of Historic Places. The park also protects a river corridor rich in wildlife, including deer, moose, beaver, migratory birds, owls, and occasional eagles.