If you come to northeastern Minnesota, there are a fair amount of quiet roads to enjoy. The area south and west of Duluth has some nice routes (Hwy 23, Willard Munger Trail, and plenty of quiet county roads in Carlton County. If you go north of Duluth, the old road along Lake Superior to Two Harbors is quite pretty and has good shoulders, although there will be traffic on a nice day. Highway 61 northeast of Two Harbors, while spectacular, is heavily traveled this time of year, and wouldn't be my first choice (except between Grand Marais and the border). But there are some wonderful quiet roads going inland from Two Harbors and the Beaver Bay area through boreal forest, although services are pretty scanty on some of the roads.
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