Park Prisoners The Untold of Western Canada's National Park, 1915-1946 Resource Type: Book Published: 1995 The story of the labour camps that once existed in Canada's mountain and prairie national parks. Between 1915 and 1946, some ten thousand men were put to work in western Canada's national parks. They were the country's unwanted: unskilled foreign workers, the jobless and the homeless, conscientious objectors, perceived enemies of the state, and prisoners of war.