 On October 25, 1963, the Sarnia Bypass was opened to traffic.By 1965, the bypass was renumbered as the northern end of Highway 40; the former route on the west side of Sarnia, via Brock Street, Vidal Street and Front Street, was subsequently renumbered Highway 40B.During the early 1970s, the province extended Highway 40 along Kent County Road 11, to meet with Highway 3 in Blenheim, Ontario, adding 17 km to the roadway's distance.