British Columbia is the westernmost province of Canada. Originally politically constituted as a pair of British colonies, British Columbia joined the Canadian Confederation on July 20, 1871. Perhaps the most influential historian of British Columbia has been Margaret Ormsby. In British Columbia: A History (1958) she presented a structural model that has been adopted by numerous historians and teachers. Chad Reimer says, "in many aspects, it still has not been surpassed". Ormsby posited a series of propositions that provided the dynamic to the history:

When did british columbia became part of canada? OK. Let's think. My stream of consciousness:
To answer the question, consider the following: Originally politically constituted as a pair of British colonies, British Columbia joined the Canadian Confederation on July 20, 1871. The answer is July 20 , 1871.