The British North America Act of 1867 was the act that established the Dominion of Canada, by the fusion of the North American British colonies of the Province of Canada, Province of New Brunswick, Province of Nova Scotia. The former subdivisions of Canada were renamed from Canada West and Canada East to the Province of Ontario and Province of Quebec, respectively. Quebec and Ontario were given equal footing with New Brunswick and Nova Scotia in the Parliament of Canada. This was done to counter the claims of manifest destiny made by the United States of America, for the defense of Britain's holdings. American claims are evinced by the invasions of the Canadas during the British-American War (1812) and the British-American War (1776).

Prior to the BNA Act of 1867, the British colonies of the Province of New Brunswick, Province of Nova Scotia, and Province of Prince Edward Island, discussed the possibility of a fusion to counter the threat of American annexation, and to reduce the costs of governance. The Province of Canada entered these negotiations at the behest of the British government, and lead to the ambivalence of the Province of Prince Edward Island, which later joined the new Dominion. The constitutional conference, ironically, was held on Prince Edward Island, in Charlottetown.