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US-24
M-24 Route Marker On to Next Route:
Former US-25
Southern Terminus:    I-75 at Exit 81 (at jct I-75 & BL I-75) in Auburn Hills northeast of Pontiac
Northern Terminus:    M-25 in downtown Unionville (cnr Center St & Bay St)
Length: 74.30 miles
Map: Route Map of M-24
Notes: A northerly extension of M-24 between Caro and Unionville was completed in 1997. Much of the southern portion of this new extension was built on new alignment north of Caro, while the remainder runs along Unionville Rd, partially replacing the M-138 designation between the junction with that highway and M-25 in Unionville. M-24 was extended, in part, to provide an all-weather route between M-81 and M-25. All-weather highways are important in Michigan's Thumb region, as the production of sugar from sugar beets is a leading industry in the area.
  Before the extension from Caro to Unionville was complete, M-24's length from Auburn Hills to Caro was 59.57 miles.
  While M-24 and US-24 seem to pass by rather closely (and at one time,US-24's northern terminus was also M-24's southern terminus), M-24 was never a part of US-24, nor was it intended to be. The two similar and nearby designations is a remnant from an era when the State Highway Department created similar situations elsewhere, including US-25 meeting M-25 at Port Austin, US-131 meeting M-131 (now M-119) at Fife Lake and later Petoskey, and US-112 and M-112 co-existing between Ypsilanti and Detroit.
  New! In "State Trunkline Needs, 1960–1980," a set of maps prepared by the State Highway Dept's Office of Planning, Programming Division in 1960 showing possible additions, upgrades and improvements to the state trunkline system over the ensuing twenty years, MSHD staff largely left M-24 as-is along its 1963–1997 alingment, with the three primary exceptions being:
  • The planning maps showed the segment of M-24 along Opdyke Rd from M-59 north to (then-proposed BL I-75) Perry St on the east side of Pontiac as being turned back to local control, as it would be in 1963.
  • The maps interestingly showed M-24 along Opdyke Rd from M-59 south to Square Lake Rd as remaining on the state trunkline highway system, although it can be easily assumed the route designation would have changed to something other than M-24 (otherwise that route would've been discontinuous). What that designation would have been is unclear, however. In 1963, though, all of Opdyke Rd would be transferred to local control in 1963.
  • In Tuscola Co, no northerly extension of M-24 from Caro northerly to Unionville is shown on the 1960 planning maps as such an extension was not conceived of until later in the decade. Indeed, all of M-138 was shown as a trunback candidate, including the portion which would be supplanted by the M-24 extension in the 1990s. The Caro–Unionville extension, however, was shown on statewide trunkline planning maps by 1968, with the remainder of M-138 still shown as a turnback candidate.
History: 1920 – The "original" M-24 in Michigan runs along a route considered to be the "classic" routing of M-20 from Muskegon to Midland via Fremont, Big Rapids and Mount Pleasant, then southeasterly along what later became US-10 then M-47 into Saginaw. In a sense, the first iteration of M-24 is somewhat of a "northern alternate" route to M-46, which also runs between Muskegon and Saginaw.
  1922 – M-24 is realigned in eastern Isabella and western Midland Counties. From Shepherd Rd, M-24 now turns northerly from Broadway Rd to Pickard Rd, then continues easterly on Pickard Rd (Isabella Co) and Isabella Rd (Midland Co) into Midland. The former route along Remus and East County Line Rds (Isabella Co), and along Salt River, Miller and Chippewa River Rds (Midland Co) are turned back to local control.
  1926 – With the debut of the US Highway system in Michigan, many route designation changes occur across the state. One such change is the redesignation of all of M-24 from Muskegon through to Midland as a new routing of M-20. Much of what had been M-20 is now part of US-10. From Midland to Saginaw, the remainder of the "original" M-24 becomes part of US-10. The M-24 designation is immediately reapplied, though in what seems to be two disconnected segments at first. From the northern terminus of the new US-24 at Pontiac, M-24 now runs along what had been M-36 northerly through Oxford to M-21 at Lapeer. M-24 then picks back up at M-38 in downtown Vassar and runs northwesterly to end at M-29 (present-day M-25) in Bay City.
  c.1927–30 – While a more permanent routing is under contemplation, M-24 is temporarily routed west from the northern end of the southern segment in Lapeer along M-21 to Davison, then northerly with M-15 to Vassar and the southern end of the northern segment. This solves the discontinuous problem noted above.
  1930 – M-24 is realigned to its own routing north of Lapeer, running northerly from M-21 at Lapeer to M-38 at Mayville, then turning westerly, follows along M-38 into Vassar.
  1933 – A new alignment of M-24 is completed from Dryden Rd at Metamora to Lapeer. The old route along Metamora, Hunters Creek and Clark Rds is turned back to local control.
  19___ – A new alignment of M-24 is completed from Metamora Rd north of Oxford to Dryden Rd at Metamora. The old route along Metamora Rd is turned back to local control.
  1934 – From Vassar to its northern terminus at Bay City, M-24 is concurrently designated with M-15.
  1936 – A new M-24 eastern bypass of Pontiac is completed when the M-24 designation is transferred to Opdyke and Square Lake Rds along Pontiac's eastern and southern boundaries, continuing westerly along Square Lake Rd to its terminus at jct M-58 & US-24/Telegraph Rd. The former route of M-24 through downtown Pontiac along Perry St, Parke St and Woodward Ave is designated M-24A.
  1940 – Around this time, the State Highway Department begins embracing a new type of route designation: the Business Connection (e.g. Business Routes, Loops and Spurs). In late 1940, M-24A through downtown Pontiac is, accordingly, redesignated as BUS M-24.
  1942 – The northern end of M-24 is shifted away from Bay City and, instead, toward Caro. Formerly running northwesterly from Mayville to Bay City via Vassar and Richville, M-24 now runs due north from M-38 to end at M-81 in downtown Caro. The fromer route of M-24 along M-38 between Mayville and Vassar retains the M-38 designation, while the concurrent segment with M-15 from Vassar to Bay City retains the M-15 designation.
  1949 – In mid-1949, a new alignment at Mayville simplifies the routing of M-24, which now enters the town from the east instead of the south.
  1950 – M-24 is realigned on the north side of Lapeer, from Saginaw Rd onto a newly constructed portion of Lapeer Rd.
  1953 – M-24 is realigned onto a new highway bypassing the downtown area of Mayville and shaving more than ½-mile from the route.
  1957 – The final 5 miles of gravel-surfaced M-24, south of Caro, are paved.
  1961US-10 is realigned to bypass Pontiac to the west replacing the M-58 designation in its entirety. Due to this, the former M-24/M-58 segment of Square Lake Rd becomes US-10/M-24, while the former US-10/BUS M-24 segment of Woodward Ave becomes BUS US-10/BUS M-24.
  1963 – With the completion of I-75 around the east side of Pontiac, M-24 is scaled back to end at jct BL I-75 at the I-75 connector at Exit 81 on the northeast side of Pontiac. The former M-24 along Opdyke Rd on the east side of Pontiac is turned back to local control, while the former route along Square Lake Rd between Opdyke and Woodward Ave becomes a part of the newly-designated BL I-75. The remaining portion of the former BUS US-10/M-24 along Square Lake between Woodward and Telegraph Rd becomes just a portion of BUS US-10. All of BUS M-24 through downtown Pontiac becomes a part of the new BL I-75. This is the first time since the mid-1920s that US-24 and M-24 do not touch.
  c.1992 – M-24 is rerouted from E Frank St onto Ellington St in Caro in preparation for the completion of the M-24 extension.
  1997 – The M-24 extension north of Caro opens to traffic. From M-81 in Caro, the extension runs northerly for 1½ miles via Cleaver Rd, then westerly for 4 miles on newly-built highway, then northerly again along Unionville Rd to M-138 east of Akron. From there, M-24 replaces the M-138 designation northerly into Unionville.
Controlled Access: No portion of M-24 is freeway or expressway.
NHS: From I-75 at Exit 81 northeast of downtown Pontiac to I-69 at Exit 155 south of Lapeer.
Photographs:  
Weblinks:
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