The plan is to drive to Baudette, MN by way of Canada's Hwy 1.  Neither Cathy nor I have driven this route and we hope to see a different look than the interminable "big sky" of Montana and western North Dakota.  From Baudette (with my rear bike tire touching the Canadian border) I'll ride to Bemidji, MN.  After that, the route will follow the Mississippi beginning with the headwaters in Lake Itasca.  It will take us a few extra days to get out of Minnesota because we have friends and relatives of Cathy to visit, at least one of whom wants to ride a bit with me.

The route is laid out comprehensively in Bob Robinson's book 

Bicycling Guide To The Mississippi River Trail: A Complete Route Guide Along The Mississippi River

Other than beginning in Minnesota and ending in Louisiana, we don't yet know the full route.  Bob's book covers both sides of the river and I am sure we will cross it more than once.  I do know we plan to cross to Wisconsin after leaving Minneapolis but after that, all bets are off.