When did Qubec join Confederation?

Answer 1

Québec did not "join" Confederation. Prior to Confederation, there were several British colonies in British North America, among which were the Province of Nova Scotia, the Province of New Brunswick and the pre-Confederation Province of Canada.1

The former Province of Lower Canada, which later became Québec, was part of the pre-Confederation Province of Canada, which also included the former Province of Upper Canada.2

The three provinces, Nova Scotia, New Brunswick and Canada, formed a new "dominion" called Canada on July 1, 1867, through section 3 of what was then known as the British North America Act (now the Constitution Act). Section 5 of the BNA Act then divided Canada into four provinces: Nova Scotia, New Brunswick, Ontario and Québec.

Section 6 of the BNA Act then deemed that the pre-Confederation Province of Canada was severed into two separate provinces. The former Province of Upper Canada constituted the Province of Ontario and the former Province of Lower Canada constituted the Province of Québec.

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Notes:

1. The other British colonies were Newfoundland, Prince Edward Island, British Columbia, and the Hudson's Bay Company proprietary colony known as Rupert's Land. The territory north of Rupert's Land, including the Arctic islands, was also British.

2. The Province of Upper Canada and the Province of Lower Canada had ceased to exist as separate entities when the Act of Union, which united them as the Province of Canada, was proclaimed on on February 10, 1841. Between February 10, 1841, and July 1, 1867, the former Upper Canada was referred to as "Canada West" and the former Lower Canada was referred to as "Canada East."

Answer 2

1867