Engraving of the locks at Bytown (Ottawa).
The canal connects Ottawa in the north with Kingston in the south. It is the oldest continuously operated canal system in North America, and in 2007, it was registered as a UNESCO World Heritage Site.
During the War of 1812, American forces were ordered to capture Kingston. This would have cut off supply routes to communities in Upper Canada to the west. Fortunately, American forces never carried out those orders. Realizing the dangers, the British decided to build up the defenses in Kingston and develop a river transport route well away from the United States border.
Construction of the Rideau Canal started in 1826 under the supervision of Lieutenant-Colonel John By of the Royal Engineers, and was completed in 1832 at a cost of £822,000. As many as a thousand people died during construction, mainly from malaria.
When opened in 1832, it became a popular waterway and was used to carry immigrants traveling west and for heavy goods heading east to Montréal. It was never actually needed for military purposes as the risk of armed conflict subsided. By 1849, a series of locks was built along the St. Lawrence river, and commercial shipping switched to the more direct route between Kingston and Montréal.