

In 2011 the city had the highest level of particulates air pollution of any Canadian city, but it has since dropped to rank 30th in this hazard. The complex of refining and chemical companies is called Chemical Valley and located south of downtown Sarnia. Because Oil Springs was the first place in Canada and North America to drill commercially for oil, the knowledge that was acquired there resulted in oil drillers from Sarnia travelling the world teaching other enterprises and nations how to drill for oil. The natural port and the salt caverns that exist in the surrounding areas, together with the oil discovered in nearby Oil Springs in 1858, led to the dramatic growth of the petroleum industry in this area.

Located in the natural harbour, the Sarnia port remains an important centre for lake freighters and oceangoing ships carrying cargoes of grain and petroleum products. This was the first time that a vessel other than a canoe or other oar-powered vessel had sailed into Lake Huron, and La Salle's voyage was germinal in the development of commercial shipping on the Great Lakes. He named the site "The Rapids" on 23 August 1679, when he had horses and men pull his 45-ton barque Le Griffon north against the nearly four-knot current of the St. The site's natural harbour first attracted the French explorer La Salle. Clair River in the Southwestern Ontario region, which forms the Canada–United States border, directly across from Port Huron, Michigan. Sarnia is located on the eastern bank of the junction between the Upper and Lower Great Lakes where Lake Huron flows into the St.

It is the largest city on Lake Huron and in Lambton County. Sarnia is a city in Ontario, Canada, with a 2016 population of 71,594.
