For the provinces in southern Canada, Backroad Mapbooks offers SD cards for Garmin GPS units
http://www.backroadmapbooks.com/GPS/index.htmlTheir maps are excellent. These maps also show hiking trails, campsites, recreational opportunities, fishing spots, etc.
Unfortunately, no product available for Yukon or Alaska. And the northern mapping from Garmin is very out-of-date, but then the topographic paper mapping offered for the north is also out-of-date. It isn't uncommon for the GPS mapping to show the highway in an entirely different location then it actually is because new sections haven't yet been mapped. Fortunately, there isn't much route choice and few road junctions on which to get confused.