Really depends on whether you are staying in Canada or crossing over to the US. If I were doing your trip, I would take US I-69 to I-75 and Sault Ste. Marie. That avoids Chicago by completely avoiding all of Illinois. If you have traveled west on the Trans-Canada Hwy. before, then take the Michigan Upper Peninsula route south of Lake Superior to International Falls, MN, circle around gorgeous Lake of the Woods, and head to wildlife-rich Riding Mountain National Park NW of Winnipeg. The RMNP campground in Wassagaming has fairly private, long pull-thru, FHU sites, good cell service and the best WiFi we have found in a public campground.
You should get to Banff and Jasper NPs either going to, or coming from, Vancouver if you haven't been there before. However, we were once in a snowstorm in Banff NP in mid-Sept., so it may be a little late by the time you get there. You could also stay farther south and visit Waterton Lakes NP on your way to the glacial lakes, orchards, wineries, and great restaurants of the Okanagan Valley (where we will be on an early Sept. trip!).
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