 In 1970, I-75 through Detroit was completed, and two additional sections of M-76 were converted to freeway.The northern section ran from the US 27-to-I-75 transition south of Grayling to the Crawford–Roscommon county line, and the second was an extension from Alger to the West Branch area.The first ice-detection system in the state was installed on the River Rouge bridges in the Detroit area in an attempt to maximize driver safety.