 County Road 510 ( CR 510 , Co . Rd . 510 ) is a primary county road in Marquette County , Michigan , that connects Marquette with the community of Big Bay . The road runs through rural forests as a paved and dirt road in northern Marquette County . It crosses the Dead River near the Hoist and McClure dams and runs for 26 @.@ 103 miles ( 42 @.@ 009 km ) before terminating at an intersection with CR 550 south of Big Bay . 
