State Route 640 (SR 640, OH 640) is an east–west state highway in the northeastern portion of the U.S. state of Ohio. State Route 640 has its western terminus is at a signalized intersection with State Route 283 (Lakeshore Boulevard) in Willowick. Its eastern terminus is in downtown Willoughby at a signalized intersection where it meets U.S. Route 20 and State Route 174, which has its northern terminus at this same intersection.

Located entirely within the western part of Lake County, State Route 640 serves the northeastern Cleveland suburbs of Willowick, Eastlake and Willoughby. Known as Vine Street for its entire length, this stretch of roadway carried the designation of State Route 288 prior to being re-designated as State Route 640 in the early 1940s.

State Route 640 runs entirely within western Lake County in the northeastern suburbs of Cleveland. Starting at the highway's western terminus. the highway is three lanes with the center lane being a left turn lane. The highway widens to four lanes when it crosses into Eastlake, and remains four lanes for the remainer of its length. The highway contains mostly chain retailers and apartment complexes along its length. It passes just north of Classic Park near the intersection with S.O.M. Center Road.

No portion of the highway is included within the National Highway System, a network of highways deemed most important for the country's economy, mobility and defense.

In 1941, State Route 640 made its debut along the path that it maintains to this day between Willowick and Willoughby in western Lake County. State Route 640 replaced the stretch of roadway that was designated as State Route 288 prior to 1941. No changes of major significance have taken place to the route since its inception.

The entire route is in Lake County.