Vivian you might try a combination of the Northern Tier and North lakes routes, you could continue on to Sault St. Marie from the UP of Michigan.
orth Lakes Bicycle Route is very pleasant to do if you like biking through hardwood forests, lakes and farmlands. Its beauty is subtle rather than dramatic. It's a route in which high-mileage days are possible, if you are so inclined, because it is not particularly difficult. If you are doing the Northern Tier, you can use sections one and two along with the Lake Erie Connector instead of dropping south and going through Iowa, Illinois, Indiana, and Ohio. The Manitowoc Alternate uses a ferry across Lake Michigan and shortens the route by about 200 miles. The ferry is pricey, so call for more information before you decide to ride the alternate.
If you are beginning in Minneapolis-St. Paul, you can conveniently start the route by biking right out of the Minneapolis-St. Paul International Airport onto bike paths along the Minnesota and Mississippi rivers. The route uses city streets and connects to the Willard Munger State Trail, a beautiful bike trail that leads you out of the Twin Cities metropolitan area. You'll cross the St. Croix River into Osceola, Wisconsin. The route goes through dairy farmland and makes a gradual transition to the hardwood forests and lakes in the northern part of the state.
After Wisconsin, you'll bike through the farmlands of the Upper Peninsula in Michigan and ride alongside Lake Michigan. At St. Ignace, a ferry takes you across the Mackinac Straits into Lower Michigan. But be sure to take some time for a visit on Mackinac Island, and do the short eight-mile loop around the island. You'll share the road with only horses and buggies, pedestrians, and other bicyclists as motorized vehicles are banned from the island. The area between Mackinaw City and Traverse City, at the northern tip of Lower Michigan, is a favorite spot for vacationing tourists. The route traverses farmlands and woods as you head southward toward Indiana. As you enter Indiana, LaGrange County is home to a large Amish community, where you'll share the road with the horses and buggies. Asphalt roads in this area have grooves worn in them from horses' hooves, so you need to ride carefully. When you end your trip in Monroeville, you can stay at the Shelter House in Monroeville Community Park. It's a "full service" shelter with kitchen facilities, showers, and lots of floor space for your sleeping bag, set up specifically for cyclists. From here, you can rejoin the Northern Tier heading east or west.