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Events from the year 1821 in Canada.
Incumbents
- Monarch: George IV
Federal government
- Parliament of Lower Canada: 11th
- Parliament of Upper Canada: 8th
Governors
- Governor of the Canadas: Robert Milnes
- Governor of New Brunswick: George Stracey Smyth
- Governor of Nova Scotia: John Coape Sherbrooke
- Commodore-Governor of Newfoundland: Richard Goodwin Keats
- Governor of Prince Edward Island: Charles Douglass Smith
Events
- July 17 – Construction of the Lachine Canal in Montreal begins.
- July – The Hudson's Bay Company merges with archrivals, the Montreal-based North West Company, creating unemployment for a substantial proportion of their Métis workforce.
- No foreigners allowed in Russian-American waters, except at regular ports of call.
thumb|right|150px|John Abbott
Births
- February 21 – John Beverley Robinson, politician (d.1896)
- March 12 – John Abbott, politician and 3rd Prime Minister of Canada (d.1893)
thumb|right|Charles Tupper
- July 2 – Charles Tupper, politician, Premier of Nova Scotia and 6th Prime Minister of Canada (d.1915)
- July 6 – Henri Bernier, politician, businessman and manufacturer (d.1893)
- August 13 – Philip Carteret Hill, politician and Premier of Nova Scotia (d.1894)
- August 18 – Maurice Laframboise, lawyer, judge and politician (d.1882)