There is a considerable amount of truck traffic on Prairie roads, particularly the Trans-Canada highway. This is hardly unexpected. I must also add that Prairie truckers are generally very considerate towards cyclists and very often pull over into the far lane when passing, even though there is a lovely wide shoulder as the following picture demonstrates.
One thing that I found curious (and by curious, I mean "fascinating" rather than "wrong") were the diverse natures and size of some of the over-sized loads being hauled along. One of the more interesting was a light aircraft with its wings removed which went by somewhere in Saskatchewan before I could photograph it. Other loads included a large-ish house...
loading gauge!" (A loading gauge is the maximum size a train can be before hitting things beside or over the track.)
The man who rented me a motel room in Treherne, Manitoba, told me that he was only helping a friend by being the clerk for the motel. His "real" job was driving a pilot truck. Pilot trucks are the pickup trucks that often precede or follow over-sized loads to give warning of the behemoth to come. I suspect they also keep a look out for any bits of the route that are too small for the load so as to give the truck hauling it time to stop.