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. 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. 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. 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 complex of refining and chemical companies is called Chemical Valley and located south of downtown Sarnia. 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. About 60 percent of the particulate matter comes from industries and polluters in the neighbouring United States