The first sections of freeway for I-75 were opened in 1957, beginning with the southern section near the Ohio state line opened in October 1957. The Mackinac Bridge was opened to traffic on November 1, 1957; a new section of freeway and an interchange connected US 2 to the bridge on the northern end, and to US 27 and US 31 on the southern end. The MSHD formally proposed the I-75 number in 1958. On June 30 of that year, the first stretch of the "Fenton–Clio Expressway" opened. Construction on the Chrysler Freeway in Detroit started on January 30, 1959. The I-75 signs were first installed along the Detroit–Toledo Expressway in October 1959, replacing US 24A signage in the Monroe area, after the state waited for final approval of the numbering system to be used in the state.