Interstates with No Auxiliary Routes by FlaxmanR

Question 10

A somewhat rare case of an interstate designation taking over for a US highway with the exact same number, this US highway formerly ran from Miami all the way to Copper Harbor, Michigan. Since 2015, however, the US highway functionally does not exist as a separate entity between a couple miles south of the Wisconsin border and a point just north of Green Bay where it takes back over from the signed interstate. What number do the interstate and the US route (also notable as the US route that encompasses Lake Shore Drive in Chicago) share?