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M-22 & M-109 junction route signage in Glen Arbor, Michigan
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Former M-107
M-108 Route Marker On to Next Route:
M-108 is a former state trunkline route existing from June 28, 1928 until December 9, 2010.
Southern Terminus*:    I-75/G Mennen Williams Frwy at Exit 337 at Mackinaw City
Northern Terminus*:    Cnr of Nicolet St & the northbound I-75 off-ramp at Exit 338, between the Michigan Welcome Center and Central Ave in Mackinaw City.
Final Length*: Updated 1.158 miles
Maps: Route Map of Former M-108
Mackinaw City State Trunkline History [slow connections]
Mackinaw City State Trunkline History [fast connections]
Notes: * The termini and final length for M-108 reflect the beginning and ending of the route and its length as of the time of its decommissioning in late 2010.
  Before the completion of the Mackinac Bridge in November 1957, M-108 served as the state trunkline route connecting US-23/US-27 and US-31 at the State Highway Ferry Docks to the Fort Michilimackinac State Historic Park. Interestingly, M-108 was a "three-legged" route at Mackinaw City for many years. See the "1928" listing in the History section below for details.
  Updated In 2010, all of M-108 was transferred to local (county and village) control and is no longer a state trunkline highway route. The reason for the transfer, according to Mackinaw City Village Manager Jeff Lawson was "the stretch [M-108] is too small to meet federal guidelines to be considered a highway, which led to MDOT turning it over to the village after reconstructing it." However, no such guidelines are known to exist, so this explanation may have based on a possible misunderstanding. Federal funding of highways is not based on how "small" or "large" a highway is, but rather its purpose and function. Indeed, 50-plus mile long rural, gravel roads may get no federal funding while 1.14-mile long I-375 in downtown Detroit—even shorter than former M-108 was!—is an important part of the (largely federally-funded) Interstate highway system. If anything, MDOT likely felt the purpose and function of M-108 no longer met its current definition of a state trunkline highway, although it provided a connection between northbound I-75 and southbound US-23 as well as served the traffic heading between I-75, US-23 and the popular Michigan Welcome Center at Mackinaw City. In the end, M-108 was a state trunkline route for 79 years total: 1928–1957 and 1960–2010.
  The only portion of the modern (1960–2010) route of M-108 which coincided with its historic routing (1928–1957) was that portion along Nicolet St from Old 31 (just south of the US-23 intersection) northerly to its northern terminus.
  Animated maps showing the evolution of M-108 at Mackinaw City in relation to the other signed state trunklines in the area are available under the "Maps" section above.
  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 showed the route of M-108 mostly how it appeared during its 1960–2010 incarnation. The maps, however show M-108 as possibly continuing northerly along Nicolet St to Central Ave, then turning west on Central and terminating at the I-75 overpass (no interchange at this location). Whether that was an intentional depiction or a cartographic error is not clear.
History: 1928 (Jun 28) – A new "three-legged" state trunkline routing is created in the Village of Mackinaw City. First, a new angled "cut-off" route linking US-31 at Nicolet St with US-23/US-27 along Huron St is created and the route of US-31 is transferred to the new "cut-off" to Huron St where a three-way concurrency of US-23/US-27/US-31 leads up to the State Ferry Docks. From the intersection of the new US-31 "cut-off" and Nicolet St on the south side of town, a new M-108 is commissioned via Nicolet St northerly to Central Ave, then turning easterly via Central for 3 blocks to Huron St, then southerly via Huron St to the State Ferry Docks and a jct with US-23/US-27/US-31. This forms a "U-shaped" route. Second, the 5-1/2 blocks of Nicolet St from the cnr of Central Ave northerly to a turnaround at the tip of Old Mackinac Point are transferred to the state and become the third "leg" of M-108. Thus, motorists travelling westerly via M-108 on Central Ave through downtown each the intersection of Nicolet St and can choose to turn left onto M-108 southbound or right onto M-108 northbound! See the companion map M-108: Original Configuration for a graphical represenation.
  1955 (May 25) New! – State Highway Commissioner Charles M. Ziegler announces the plans for state trunkline changes in Mackinaw City with regard to the building of the Mackinac Straits Bridge. Ziegler outlines the path of the southerly approach will lie to the west of M-108 and pass over Huron and Central Aves and the Pennsylvania Railroad before connecting with both US-31 and US-23/US-27 in the southern part of the village. This will likely result in a southerly extension of M-108 from its current terminus at US-31.
  1957 (Oct 21) – Just 11 days before the brand-new Mackinac Bridge opens to traffic between Mackinaw City and St Ignace, all two miles of all three legs of M-108 are transferred to local control. This same day, the routes of the Mackinac Bridge approach (present-day I-75) and connector to US-23/US-27 are officially transferred to state control.
  1960 (Jul 6) – Less than three years after being transferred to local control, a portion of the former route of M-108 is re-transferred as a state trunkline route. This time, the "new" M-108 begins at I-75/US-31 Exit 337 south of Mackinaw City and continues northerly via Nicolet St to point 1.158 miles north of its point of beginning, just south of the Pennsylvania RR or two blocks south of Central Ave.
  2010 (Dec 9) New! – The entire length of M-108 is transferred to local control and ceases to be a state trunkline highway route. The MDOT transfer documentation specifically notes the portions being transferred to the Emmet County Road Commission and the Village of Mackinaw City. The southern portion becoming a County Primary road "from its southern terminus approximately located at a point where the M-108/Mackinaw Highway centerline and the center of southbound I-75 freeway would cross if there were no grade separation between the roadways, northerly to the south city limits of the Village of Mackinaw City, a distance of about 0.32 miles." The northern portion becoming a City Major street "from the south city limits of the Village of Mackinaw City northerly to the northern M-108 terminus located at the I-75 northbound exit ramp, a distance of about 0.75 miles." The reason for the transfer, according to Mackinaw City Village Manager Jeff Lawson is "the stretch [M-108] is too small to meet federal guidelines to be considered a highway, which led to MDOT turning it over to the village after reconstructing it." (See additional discussion in "Notes" section above.)
Controlled Access: New! No portion of former M-108 upon decommissioning existed as freeway or expressway.
NHS: Updated The portion of former M-108 between I-75 at Exit 337 and US-23 is on the National Highway System (NHS) as an Intermodal Connector.
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