When the Dominion of Canada was created in 1867, the region of British Columbia at that time did not join Canada. Geographically isolated from the rest of the country by North America’s largest mountain range, the Rocky Mountains, BC was almost cut off from all contact with the eastern region of Canada. BC was seriously considering joining the US unless Canada would undertake the construction of a railway across the Rocky Mountains to connect BC with the other provinces. In 1871, when Sir John A. Macdonald, Canada’s first Prime Minister, promised to build a Canadian Pacific Railway within ten years, BC finally agreed to join Confederation.