 At the same time the M-29 designation was shifted to the eastern side of the state, generally where it exists today.However, rather than terminating in Marysville, the route continued all the way around the thumb and into Bay City on a route now occupied by present-day M-25.In 1933, the US 25 designation was extended from Port Huron, along the existing M-29 roadway, to a terminus in Port Austin.