Located entirely within the western part of Lake County, SR 640 serves the northeastern Cleveland suburbs of Willowick, Eastlake and Willoughby.

SR 640 runs entirely within western Lake County in the northeastern suburbs of Cleveland.

The highway passes mostly chain retailers and apartment complexes along its length.

It passes just north of Classic Park near the intersection with SR 91 (S.O.M.

[2] In 1941, SR 640 was designated along the path that it maintains to this day between Willowick and Willoughby in western Lake County.