Previous designations When the state highway system was first signed in 1919, M-13 followed the general path of the modern US 131. The highway specifically ran along what is now
M-103,
US 12, the pre-freeway US 131,
M-113,
M-186, US 131,
US 31 and
M-119 between the Indiana state line south of
Mottville to
Harbor Springs. When the
United States Numbered Highway System was created on November 11, 1926, US 131 replaced M-13 from the state line north to
Fife Lake; from Fife Lake north to Harbor Springs, the highway was redesignated
M-131. In 1927, the section of
M-19 from
Brockway to
Avoca was redesignated as M-13 and extended through Avoca. During 1929, the trunkline was extended eastward to terminate at the contemporary
M-51 near Gardendale. In 1931 M-13 was redesignated as
M-136.
Current highway The
Michigan State Highway Department (MSHD) used the M-13 designation for a highway at the end of 1932 that connected
M-78 and M-21 through Lennon. By the middle of 1936, the highway had been extended northward to end at a junction with M-46 in Saginaw. The entire trunkline was paved in the middle of 1939. Later the next year, the section in Saginaw was extended a bit farther along Washington Avenue to end at a junction with
US 10 and US 23. A section of the then-M-78 freeway (now I-69) opened between 1958 and 1960; when this freeway opened, M-13 was truncated northwards slightly in the Lennon area to end at the new highway. The I-75/US 23 freeway north of the Kawkawlin area to Standish opened in 1967, and M-13 is shown on maps following US 23's former route through Linwood and Pinconning after the change. The routing of M-13 has stayed the same since. ==Major intersections==