Michigan Highway System

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Trunkline shield
State:	M-X
Interstates:	Interstate X (I-X)
US Routes:	U.S. Highway X (US X)

The Michigan State Trunkline Highway System is made up of all the highways designated as Interstates, U.S. Highways and State Highways in the U.S. state of Michigan. The system is maintained by the Michigan Department of Transportation and comprises 9,720.8 miles (15,644.11 km) of trunklines in all 83 counties of Michigan on both the Upper and Lower peninsulas, linked by the Mackinac Bridge. The system ranges in size from the unsigned BS I-375 at 0.167 miles (0.269 km) and signed M-212 at 0.732 miles (1.178 km) to I-75 at 395.40 miles (636.33 km). Some trunklines in Michigan are maintained by MDOT but bear no signage along the route to indicate this. These unsigned trunklines are mostly segments of former highway designations that have been moved or had the designations decommissioned. These segments remain under state control until the appropriate city or county accepts jurisdiction of the roadway from the state.

1 Usage
- 1.1 Numerical duplication
2 Highway systems
3 History
4 See also
5 References
6 External links

[edit] Usage

This is a map of highways in the state of Michigan, however not all highways are in the map, nor are they all totally accurate.

The M in the state highway numbers is an integral part of the designation and included on the reassurance marker shields posted along the side of the highway. Michigan highways are properly referred to using the M and never as "State Route 28" or "State Highway 66". Michigan is one of only two states that does this, the other one being Kansas. This usage dates from 1918, when Michigan's state trunklines were first signed in the field. The state highway route marker is a diamond with a block letter "M" at the top.

Although "M-nn" outside of Michigan could refer to other state, provincial, local, or national highways, local usage in those areas does not mimic the Michigan usage in most cases. In the United Kingdom, "M" refers to motorways, analogous to freeways in the United States, whereas "M-nn" designations in Michigan simply signify state trunklines in general and may exist on any type of highway. "M-nn" trunklines are designated along eight-lane freeways in urban areas, four-lane rural freeways and expressways, principal arterial highways, two-lane highways in far-flung rural areas, and even M-185, 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 I-696 running along the northern Detroit suburbs. The lowest numbers in use are M-1 along Woodward Avenue in Detroit and US 2 across the UP. Most M-numbered trunkline designations are lower than the low 200s, 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 is to be inferred in Michigan's numbering system.

[edit] Numerical duplication

Unlike other states, there are no formal rules prohibiting the usage of the same number under different systems. Motorists driving Michigan's highways will encounter both I-75 and M-75 as well as both US 8 and M-8. Many of the U.S. Highways had their numbers duplicated with state trunklines when the U.S. Highway system was created in 1926. The coming of the Interstate Highway System in the late-1950s further illustrated this with each mainline Interstate designation having a similar, but unrelated "M-numbered" state trunkline designation elsewhere in the state. However, many U.S. Highways in Michigan have left an M-numbered highway with the same number as a relic of their existence. As an example, M-27 runs along a portion of former US 27. In addition, two occurrences of an original "M-numbered" state route which became U.S. Highways with the same route designation existed: all of M-16 became US-16 and most of M-10 from Detroit to Saginaw was assumed into the route of US 10 in 1926. In fact each iteration of M-10 has existed along a former or future alignment of US 10, at least in part.

[edit] Highway systems

There are four systems of highways maintained by MDOT as part of the state trunkline system. In addition there are systems of roads maintained by the federal government and counties. There is considerable overlap as designations from different systems share the same stretch of pavement in concurrencies. I-75 and US 23 share around 75 miles of freeway alignment between Flint and Standish. BUS US 131 in Big Rapids is routed long a portion of M-20 on Perry Street to connect back to the US 131 freeway.

[edit] Interstate Highways

Main article: List of Interstate Highways in Michigan

I-96

[edit] U.S. Highways

Main article: List of U.S. Highways in Michigan

US 10

[edit] State trunklines

Main article: List of Michigan trunklines

[edit] Bannered routes of the Michigan Trunkline System

Main article: List of bannered highways in Michigan

BUS M-60

Another important part of the state trunkline system is the bannered highways. These highway designations are distinguished by the "banner plate" on top of the normal highway marker indicating them as business or connector routes of the system. Business loops and spurs of the Interstate Highway System use a special green version of the standard Interstate marker which places the word "Business" at the top where "Interstate" appears normally. These business loops and spurs connect downtown districts to the main highways after realignments and bypasses have routed the main highway out of the downtown area. Other highways are the connector routes which as the name suggests, connect two highways together. Most of these connectors are unsigned.

[edit] County highways

Main article: List of Michigan County-Designated Highways

C-66

There exists a parallel system of county-designated highways in Michigan with numbers assigned in a grid system by MDOT. These highways, while signed on the trunklines and shown on the official MDOT map are maintained by the various counties. They were started in 1970 as a supplement to the main trunkline system. They carry a letter-number combination and used the national standard pentagon-shaped marker in blue and yellow. Other county systems are designated and maintained in each of the 83 counties and practices vary between using the pentagon marker to older square markers in black and white.

[edit] Other systems

Federal Forest Highway 16

The Forest service maintains Forest Routes providing access to the National Forests in the state. A handful of these highways exist in Michigan. In addition to these, Michigan participates in the Great Lakes Circle Tour program, signing these tours along the state-maintained highway closest to Michigan's Great Lakes shorelines.^[1] There is also the Michigan Heritage Route system created in 1993 to highlight trunklines with Historic, Recreational or Scenic qualities.^[2]

[edit] History

While Michigan was the second jurisdiction to post route designations along its state trunkline highway system in 1919 (neighboring Wisconsin was the first a year earlier in 1918), Michigan actually began assigning internal trunkline route designations for internal inventory purposes as early as 1913. From 1918 to 1926, only the "M-numbered" route designations existed on state highways throughout Michigan, while the coming of the U.S. Highway System in 1926 caused several existing designations to be either reassigned or retired altogether. All single-digit state trunkline designations (e.g. M-9) were removed from the system in the late-1930s, purportedly reserved for a proposed "Superhighway" system in early planning stages at the time, never built due to the coming of World War II. (The Michigan Department of Transportation began reassigning single-digit route designations in the 1970s on mostly urban trunklines.)