page_title: Michigan State Trunkline Highway System
section_title: Usage
hierarchical_section_title: Michigan State Trunkline Highway System / Numbering / Usage
caption_attribution_description: English: The "Welcome to Michigan" sign on US Highway 8 in Dickinson County, Michigan
context_page_description: The State Trunkline Highway System consists of all the state highways in Michigan, including those designated as Interstate, United States Numbered, or State Trunkline highways. In their abbreviated format, these classifications are applied to highway numbers with an I-, US, or M- prefix, respectively. The system is maintained by the Michigan Department of Transportation and comprises 9,669 miles of trunklines in all 83 counties of the state on both the Upper and Lower peninsulas, which are linked by the Mackinac Bridge. Components of the system range in scale from 10-lane urban freeways with local-express lanes to two-lane rural undivided highways to a non-motorized highway on Mackinac Island where cars are forbidden. The longest highway is nearly 400 miles long, while the shortest is about three-quarters of a mile. Some roads are unsigned highways, lacking signage to indicate their maintenance by MDOT; these may be remnants of highways that are still under state control whose designations were decommissioned or roadway segments left over from realignment projects.
context_section_description: The letter M in the state highway numbers is an integral part of the designation and included on the diamond-shaped reassurance markers posted alongside the highways. The state's highways are referred to using an M-n syntax as opposed to Route n or Highway n, which are common elsewhere. This usage dates from 1919, when Michigan's state trunklines were first signed along the roadways, and continues to this day in official and unofficial contexts. Michigan is one of only two states following this syntax, the other one being Kansas.
  Although M-n outside of Michigan could conceivably refer to other state, provincial, local, or national highways, local usage in those areas does not mimic the Michigan usage in most cases. In countries like the United Kingdom, M refers to motorways, analogous to freeways in the United States, whereas M-numbered designations in Michigan simply indicate state trunklines in general and may exist on any type of highway. M-numbered trunklines are designated along a variety of roads, including eight-lane freeways in urban areas, four-lane rural freeways and expressways, principal arterial highways, and two-lane highways in remote rural areas. The system also includes M-185 on Mackinac Island, a non-motorized road restricted to bicycles, horse-drawn carriages and pedestrians.
  The highest numbers used for highway designations include M-553 in the UP and Interstate 696 (I-696) running along the northern Detroit suburbs. The lowest numbers in use are M-1 along Woodward Avenue in the Detroit area and US Highway 2 (US 2) across the UP. Most M-numbered trunkline designations are in the low 200s or under, but some have been designated in the low 300s. MDOT has not assigned a designation outside the Interstate System in the 400s at this time. No discernible pattern exists in Michigan's numbering system, although most of the M-numbered routes lower than 15 are typically located in or around the major cities of Detroit and Grand Rapids.
caption: Welcome sign along US 8
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