The Canada Southern mainline ran through southern Ontario from Niagara Falls to Windsor (and Detroit), with branches to Fort Erie, Niagara On The Lake, Chippawa, Leamington, Amherstburg, Courtright, Petrolia and Edy's Mills.
The line originated as the Erie & Ontario Railroad, which was built between Niagara-On-The-Lake and Chippawa in 1854, and the Fort Erie Railway Company running between Fort Erie and Chippawa was incorporated in 1857. The Fort Erie Railway bought the Erie & Ontario in 1863, and the merged line was called the Erie & Niagara. The Erie & Niagara Extension Railway was then incorporated in 1868 to build from Fort Erie through St. Thomas to either Sandwich or Windsor. It was granted all the assets and none of the debts of the E&N. The E&NER was renamed the Canada Southern Railway in 1869.
For most of its life the Canada Southern was operated as the Canada Division or Canadian Division by the Michigan Central Railroad, which was owned by the New York Central. Most equipment used on it was lettered for the NYC but some was CSR or CS and some was MCR.