Sorry, but you need to check your facts.  The west was part of Canada was indeed part of the nation.   It was included when Canada/Britain purchased what is now the prairie provinces from the Hudson Bay Co. in 1870.  The North West Mounted Police (RCMP) were formed in 1873 by the gov't to move into the prairies to prevent encroachment by the U.S., and to provide peaceful settlement of the prairies, without an Indian War, as had taken place in the U.S.