Freight was eventually moved to railways and the St. Lawrence Seaway, but the canal remains in use today for pleasure boating, operated by Parks Canada from May through October.

[3][4] It is the oldest continuously operated canal system in North America,[5] and is a UNESCO World Heritage Site.

The name Rideau, French for "curtain", is derived from the curtain-like appearance of the falls where they join the Ottawa River.

[7] After the War of 1812, information was received about the United States' plans to invade the British colony of Upper Canada from upstate New York by following the St. Lawrence River.

To protect against such an attack in the future, the British began the construction or reinforcement of a number of defences including Citadel Hill in Halifax, La Citadelle in Quebec City, and Fort Henry in Kingston.

At the time of Jebb's survey, a water connection to Kingston had been established due to flooding created by mill dams located at White Fish Falls (today's Morton) and the Round Tail (just north of Upper Brewers), which flooded a previously non navigable area, the Cranberry floodplain.

Private contractors such as future sugar refining entrepreneur John Redpath, Thomas McKay, Robert Drummond, Thomas Phillips, Andrew White[19] and others were responsible for much of the construction, and the majority of the actual work was done by thousands of Irish, Scottish, and French-Canadian labourers.

Colonel John By decided to create a slackwater canal system[20] using dams to raise the water level to sink rapids instead of constructing new channels around them.

Because of the unexpected cost overruns, John By was recalled to London and was retired; he received no accolades or recognition for his tremendous accomplishment.

It was a major route for shipping heavy goods (timber, minerals, grain) from Canada's hinterland east to Montreal.

A simpler plan was to route around the dangerous parts of the St. Lawrence to allow direct shipping from Kingston to Montreal, and this was soon underway.

[24] By 1849, the rapids of the St. Lawrence were made navigable by a series of locks, and commercial shippers were quick to switch to this more direct route.

In the 1950s it was developed as the current Saint Lawrence Seaway, which allowed ocean-going ships access to the Great Lakes.

Today the Rideau forms part of the Great Loop, a major waterway route connecting a large area of the eastern United States and Canada.

The Rideau Canal was designated a National Historic Site of Canada in 1925, and marked with a federal plaque the next year, and again in 1962 and 2013.

In 2014, the canal appeared on a $2.50 international rate stamp as part of a Canada Post set honoring World Heritage Sites.

[34][35] In 2000 the Rideau Waterway was designated a Canadian Heritage River in recognition of its outstanding historical and recreational values.

Other plaques to the canal erected by the Ontario Heritage Trust are at Kingston Mills,[36] Smiths Falls,[37] and Rideau Lakes.

Communities along the waterway include Ottawa, Manotick, Kars, Burritts Rapids, Merrickville, Smiths Falls, Rideau Ferry, Portland, Westport, Newboro, Seeleys Bay and Kingston.

Since World War I and the construction of more extensive rail lines into rural Ontario, only pleasure craft make use of the Rideau Canal.

The original Commissariat Building and foundation of the Royal Engineers' barracks remain at the Ottawa Lock Station.

[45] The gates used on the Rideau Canal are made of Douglas Fir and are mitre-shaped to ensure a tight seal due to water pressure.

Since the winter of 1970–71, the section of the Rideau Canal passing through central Ottawa has been re-purposed as what is officially the world's largest and second longest skating rink.

[54] The cleared length is 7.8 kilometres (4.8 mi) and has the equivalent surface area of 90 Olympic ice hockey rinks.

It runs from the Hartwells Lockstation at Carleton University to the locks between the Parliament Buildings and the Château Laurier, including Dow's Lake in between.

The length of the season depends on the weather, but typically the Rideau Canal Skateway opens in January and closes in March.

When Doug Fullerton was appointed chair of the National Capital Commission, he proposed a recreational corridor around the canal, including the winter skateway between Carleton University and Confederation Park.

A small section of ice near the National Arts Centre was cleared by NCC employees with brooms and shovels,[57] and 50,000 people skated on the canal the first weekend.

[122] These machines, known as Frosters, were unveiled in 2011 and were created because Zamboni ice resurfacers that are traditionally used in hockey rinks were too small and narrow for the Rideau Canal.

[57] White ice has a milky appearance with air bubbles, and is formed when snow and water mix and then freeze.