on the National Highway System (NHS) are along the M-84 concurrency and Euclid Avenue south of Wilder Road in the Bay City area. The NHS is a network of roads important to the country's economy, defense, and mobility. History 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 first section of the US 23 freeway around Bay City opened in late 1960 or early 1961. When it opened, MSHD extended M-13 along the former route of US 23 from the northside of Saginaw into Bay City to the end of the freeway at Kawkawlin. 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 Connector route M-13 Connector (Conn. M-13) is a connector route running connecting I-75/US 23 to M-13 near the community of Kawkawlin, just