The settlement of Canada's west was greatly due to the train. The rails that quickly spread over the territory not only eased long-distance travel, but also made it possible to explore other areas that are still today almost inaccessible by other modes of transportation.

Today, the Canadian National Railway’s (CNR) main line from London and Toronto passes through Sarnia-Lambton. This railway line extends to the St. Clair Tunnel, which passes under the St. Clair River to Port Huron, Michigan. Originally built in 1891 the St. Clair Tunnel was an engineering marvel. As a key component of CN North America's seamless continental transportation strategy, the St. Clair tunnel allows direct rail access from the seaport of Halifax, Nova Scotia, to the American Mid-West. CN Rail handles about 30 trains per day including through, terminating and originating traffic.

Passenger rail traffic (Amtrak/VIA) also uses the St. Clair tunnel crossing and offers commuters in Southern Ontario a reliable mode of transportation to and from the Greater Toronto Area (GTA), as well as vacationers a gateway to travels across the continent.

For more information on passenger rail service for Sarnia-Lambton visit Via Rail.

A secondary rail line operated by CSX Transportation extends from Sarnia southward to Blenheim, south of Chatham. The line links with CN Rail in Sarnia and Chatham and with CP Rail in Chatham. The Sarnia CSX line is particularly important for the specialized servicing of the industrial chemical plants in Sarnia’s Chemical Valley and for exports to U.S. markets via Windsor and Detroit.