Same-sex marriage was legally recognized in the provinces and territories as of the following dates:
June 10, 2003: Ontario
July 8, 2003: British Columbia
March 16, 2004: Quebec
July 14, 2004: Yukon territory
September 16, 2004: Manitoba
September 24, 2004: Nova Scotia
November 5, 2004: Saskatchewan
December 21, 2004: Newfoundland and Labrador
June 23, 2005: New Brunswick
July 20, 2005 (Civil Marriage Act): Alberta, Prince Edward Island, Nunavut territory, and the Northwest Territories
Note that in some of these cases, the marriage was in fact legal at an earlier date (for example, the Ontario ruling held that marriages performed in January 2001 were legal when performed), but the legality was questioned. As of the given dates, the legality was authoritatively established.
The decision by the Ontario government to recognize the marriage that took place in Toronto, Ontario, on January 14, 2001, makes Canada the first country in the world to have a government-legitimated same-sex marriage (the Netherlands and Belgium, which legalized same-sex marriage before Canada, had their first in April 2001 and January 2003, respectively).