In 1961, the MSHD had proposed that the section of I-75 south of Detroit to Toledo be built as an electronic highway under a bid through General Motors; the testing for such a roadway was ultimately done at Ohio State University instead. That same year the original Zilwaukee Bridge, a bascule bridge across the Saginaw River was opened along with a section of freeway north to Kawkawlin. In October 1961, the first segment of I-75 near Grayling opened, connecting M-18 with the city. By the end of the year, the freeway was completed between Kinross and Dafter in the UP, and the former segment of US 27 between Grayling and Gaylord was turned back to local control. After this individual segment of freeway was completed, it left a gap between Gaylord and Indian River that was designated "To I-75" on maps for the former segment of US 27, and US 27 was truncated to about south of Grayling.