You may not recall it but it goes back over a century and continues post WWII.

Sir Clifford Sifton responsible for the Department of Immigration under Laurier promoted immigration to settle the West. Under his leadership, immigration to Canada increased significantly — from 16,835 per year in 1896 to 141,465 in 1905.  Sifton’s radical new source was eastern and central Europe.

"The policy of the government is to foster the growth of the population of Canada by the encouragement of immigration. The government will seek by legislation, regulation, and vigorous administration, to ensure the careful selection and permanent settlement of such immigrants as can advantageously be absorbed in our national economy." ~ PM Mckenzie King 1 May 1947 House of Commons

"Canada must populate or perish - that is the answer. With such great resources as we possess, and such extensive territory, we can't survive with a small population." PM John Diefenbaker on the campaign trail on April 18, 1958