King's Highway 80, commonly referred to as Highway 80, was a provincially maintained highway in the Canadian province of Ontario. It travelled in an east–west direction south of Sarnia from Courtright to Strathburn. Beginning at the St. Clair Parkway near the shores of the St. Clair River, the route travelled 69.6 kilometres (43.2 mi), intersecting Highway 40, Highway 21 and Highway 79 before ending at Highway 2. In addition to the towns at either terminus, Highway 80 serviced the communities of Brigden, Glencoe and Alvinston. The entire route was and remains two lanes wide.