History of King's Highway 80B:
King's Highway 80B was a short-lived business route serving the town of Alvinston. The route was created when Highway 80 was rebuilt on a new alignment between Walker's Corners and Highway 79 south of Alvinston. The new highway bypassed an original section of Highway 80 which passed through Alvinston. The old highway alignment was narrow, winding, had several steep grades and a one-lane bridge over the Sydenham River. Construction began on the Alvinston Bypass in 1959, and the new route of Highway 80 was completed in 1960. The old route of Highway 80 was reportedly renumbered as Highway 80B, based on recently found historical references. The highway was only in existence for a few years.
The route of Highway 80B was officially decommissioned on May 23, 1964, when the entire provincially-owned section of Highway 80B lying east of the Sydenham River Bridge was turned over to the Counties of Middlesex and Lambton. The section of Highway 80B west of the Sydenham River Bridge through Alvinston was municipally-owned. The former highway route through Alvinston followed Sydenham Street, River Street and Centre Street. It is interesting to note that the route of Highway 80B east of Alvinston was (and still is) gravel-surfaced, making it the only gravel-surfaced "B" Business Route in the history of the province. The route of Highway 80B is no longer drivable from end to end. The old one-lane bridge over the Sydenham River was demolished many years ago, and was never rebuilt.