NORTH WEST MOUNTED POLICE DUTIES

Other then the conventional duties like enforcing the law,controlling the whisky trade, the N.W.M.P  were given jobs to do and chores that had to be done, like mail delivery before the Canadian Pacific Railway (CPR) was completed, mail delivery in the Northwest Territories wasn't all that good. Mail for the Mounted Police was carried through the United States to Fort Benton, Montana, and then overland to Fort Walsh. From there, it was distributed to the various forts. Any civilian mail traveled the same route. Mounted policemen often delivered the mail once it arrived in Canada, especially in the years prior to the North West Rebellion in 1885. Mail transportation to the N.W.M.P officers became faster and easier for the officers who were given the task of mail delivery after the CPR was built.
http://www.ucalgary.ca/applied_history/tutor/calgary/nwmp.html