 US Highway 41 ( US 41 ) is a part of the United States Numbered Highway System that runs from Miami , Florida , to the Upper Peninsula of the US state of Michigan . In Michigan , it is a state trunkline highway that enters the state via the Interstate Bridge between Marinette , Wisconsin , and Menominee , Michigan . The 278 @.@ 769 miles ( 448 @.@ 635 km ) of US 41 that lie within Michigan serve as a major conduit . Most of the highway is listed on the National Highway System . Various sections are rural two @-@ lane highway , urbanized four @-@ lane divided expressway and the Copper Country Trail National Scenic Byway . The northernmost community along the highway is Copper Harbor at the tip of the Keweenaw Peninsula . The trunkline ends at a cul @-@ de @-@ sac east of Fort Wilkins State Park after serving the Central Upper Peninsula and Copper Country regions of Michigan . 
