 From there, M-72 was routed along existing roads through Williamsburg to US 131/M-66 north of Kalkaska where it followed the latter highways through downtown to bridge the gap.With this addition to the routing, the road extended "shore to shore" from Lake Huron to Lake Michigan.The Michigan State Highway Department rerouted M-33/M-72 near Fairview in late 1951 or early 1952, turning the former route back to local control.