in Canadian history, the region in Canada now known as Ontario. From 1791 to 1841 the region was known as Upper Canada and from 1841 to 1867 as Canada West, though the two names continued to be employed interchangeably.

Canada West was settled primarily by English-speaking immigrants. The inhabitants nevertheless sought confederation with Canada East (which was populated largely by French-speaking Canadians) in order to secure the unified government needed for effective administration and commercial prosperity. The government of Canada West had long been unstable when the “Great Coalition” of John A. Macdonald, George E. Cartier, and George Brown was formed and soon led to confederation. The unified Dominion of Canada was made official by the British North America Act of 1867.