Final answer:
In the 1870s, Manitoba joined the Dominion of Canada in 1870, and British Columbia followed in 1871. The promise of the Canadian Pacific Railroad was a strategic factor for British Columbia's entry, and the railway completion in 1885 was essential for Canada's development.
Step-by-step explanation:
Canadian Provinces and Territories in the 1870s
The provinces and territories that joined the Dominion of Canada in the 1870s were Manitoba, which became a province in 1870 as a home for the Métis, and British Columbia, which agreed to join the Dominion in 1871 with the promise of a transcontinental railroad. The Dominion also purchased the vast territory known as Rupert's Land from the Hudson's Bay Company in 1870, which expanded Canada's geographical size significantly and was important for railway development.
These additions to the Canadian confederation were crucial in the nation's early development. Manitoba's creation addressed the needs of the Métis people, while the promise of the Canadian Pacific Railroad was a key factor in convincing British Columbia to join. The railroad, completed in 1885, played a fundamental role in the settlement of the prairie provinces, the industrialization of Canada, and in linking its eastern and western regions.