The first railway in British North America, the Champlain and St. Lawrence Railroad, was built in the mid-1830s to 4 ft 8+1⁄2 in (1,435 mm) track gauge.
However, the promoters of St. Lawrence and Atlantic Railroad, (intended to connect Montreal to the ice-free port at Portland, Maine) decided to use 5 ft 6 in (1,676 mm), setting a precedent for the colony for several decades.
In 1867 the Great Western Railway converted to dual gauge the 229 miles (369 km) line from Windsor to Suspension Bridge, where it connected to the US network, allowing an end to transshipment at the previous break-of-gauge.
The rise in standardization with the US came about because of increasing trade across the border after the American Civil War, a process that was also underway within the US which had a greater diversity of gauges.
This previously created a break of gauge at Kennedy station, where all passengers had to disembark from the Toronto-gauge subway trains to board the standard-gauge Scarborough RT on another platform.
The former Newfoundland Railway "Newfie Bullet" Caribou (train) used three feet, six inches as its narrow gauge; these tracks have been dismantled and the right-of-way used as a T'Railway.