Sarnia, Ont, City, pop 70 876 (2001c), 72 738 (1996c), 74 167 (1991c), 72 656 (1986cA), area 164.62 km2, inc 1914. It is located at the convergence of the St Clair River and Lake Huron, 100 km west of London. A railway tunnel beneath the St Clair, car ferries and a highway bridge from nearby Point Edward connect Sarnia with Port Huron, Michigan. Sarnia is a petrochemical centre and the southern terminus of an oil pipeline from Alberta. Its government is of the city-manager type, with mayor and council elected every 3 years.