The Canadas were two British colonies, Upper Canada and Lower Canada, part of modern-day Canada. The region (formerly known as the Province of Quebec) was first divided into these colonies at the Ottawa River by the Constitutional Act of 1791, in response to the desire of recently arrived American settlers for British institutions and laws, especially British laws of land tenure, and to agitation by the English merchants of Montreal for representative government. Upper Canada corresponds to modern-day southern Ontario plus the shoreline of Georgian Bay and Lake Superior, while Lower Canada corresponds to modern-day southern Quebec; the northern majority of the current land area of these provinces was still part of Rupert's Land.
The Canadas persisted in that form until 1841, when on the basis of Lord Durham's report (1839) they were merged into the Province of Canada.