The US Highways in Michigan are the segments of the national United States Numbered Highway System^[4] that are owned and maintained by the state of Michigan,^[5] totaling 2,300 miles (3,701 km).^[1] The longest of these is US Highway 23 (US 23) at around 362 miles (583 km). On a national level, the standards and numbering for the system are handled by the American Association of State Highway and Transportation Officials (AASHTO), while the highways in Michigan are maintained by the Michigan Department of Transportation (MDOT).

The original highways were approved on November 11, 1926, by AASHTO including 14 mainline highways. A handful of these original highway designations no longer run within Michigan, and a few numbers have been added since the 1930s. Since 1999, there have been 13 mainline highways, and with the creation of a business route for Constantine, there are a total of 30 special routes in the state. Several highways have been converted to freeways, some of which are now Interstate Highways and no longer part of the US Highway System. These freeway conversions started in the 1940s and 1950s and continued through to the turn of the 21st century.

MDOT is the agency responsible for the day-to-day maintenance and operations of the State Trunkline Highway System, which includes the U.S. Highways in Michigan. The numbering for these highways is coordinated through AASHTO,^[6] an organization composed of the various state departments of transportation in the United States.^[7] Under the scheme finalized in 1926, two-digit US Highways are numbered in a grid; east–west highways have even numbers while north–south routes have odd numbers. The lowest numbers are in the east and the north. The east–west highways in Michigan number in the single digits up to the low 20s. The north–south highways range from the low 20s into the 40s. There are also three three-digit highways numbered in the 100s and one in the 200s as branches of related two-digit highways.^[8]

In Michigan, the US Highway System covers about 2,300 miles (3,701 km) of mainline highways and another 160 miles (257 km) of special routes.^[1] There are 13 mainline highways and 30 special routes in total, including one business route that is unsigned.^[8][9] Two of the mainline highways in the Upper Peninsula exit the state and re-enter, resulting in two discontinuous segments of highway for each in Michigan.^[10] The longest US Highway in the state is US Highway 23 (US 23) at just over 362 miles (583 km) spanning from the Ohio state line north to the Straits of Mackinac in the Lower Peninsula, while the shortest is the 2.3-mile (3.7 km) segment of US 8 south of Norway in Dickinson County. Special routes range in length from about 1+1⁄4 miles (2.0 km) for Business US 2 (Bus. US 2) in Ironwood to 10 miles (16 km) for Bus. US 131 in Kalamazoo.^[1]

The US Highway System was approved on November 11, 1926.^[2] At the time, 14 mainline highways were designated in Michigan.^[3] Just two years later on November 12, 1928, US 102 was renumbered as part of an extended US 141, and the former designation was decommissioned.^[11] Since then, another four designations were added in the state during the 1930s. One of these, US 112S was a suffixed, directional branch of the US 112 mainline; it was removed a few years^[12] after being designated in 1931.^[13] Around the same time period, the first alternate routes were designated, numbered with an "A" suffix.^{[lower-alpha 1]}

During World War II, the Michigan State Highway Department (MSHD)^{[lower-alpha 2]} built the Willow Run Expressway to carry workers from Detroit to the defense plants at Willow Run Airport.^[19] This expressway was numbered as a part of US 112 initially.^[20] During the 1950s, additional highways were converted to freeways before the coming of the Interstate Highway System in 1957. The first highway renumbered as an Interstate was US 24A in the southeastern corner of the state, which became part of Interstate 75 (I-75) in 1959.^[21]

Major numbering changes started in the 1960s as Michigan retired or rerouted its US Highways with the completion of Interstates. US 12 replaced US 112 in 1962 when the I-94 designation supplanted most of the original US 12.^[22] Later that year, US 16 was decommissioned in favor of I-96.^[23] This trend continued into the 1970s when US 25 was decommissioned as redundant to sections of I-75 and I-94.^[24]

Not all freeway conversions of existing US Highways resulted in the removal of US Highway numbers. In 1968, the state submitted a request for additional Interstate Highway mileage to the federal government, including a proposal to convert US 131.^[25] This specific project was not approved although the state continued its own efforts to convert the highway, including various segments opened in the 1970s^[26] and 1980s.^[27] Other highways converted to freeways included US 10, US 23, US 27, US 31 and US 127.^[8]

At the end of the 1970s, MDOT took part in a Federal Highway Administration-backed initiative called the Positive Guidance Demonstration Project, and the two agencies audited signage practices in the vicinity of the I-96/M-37 and I-296/US 131 interchange in Walker, north of Grand Rapids. MDOT determined that usage of the I-296 designation was "a potential source of confusion for motorists".^[28] Following this program, the Reflective Systems Unit at MDOT reviewed the state of two- and three-way concurrencies along the highway system in Michigan. They approached the department's Trunkline Numbering Committee and the district traffic and safety engineers on October 19, 1982, for proposals to reduce or eliminate the various overlapping designations to "avoid driver confusion and save funds".^[29] The initial discussion report included the various remaining overlaps between Interstate and US Highways.^[29] When the unit released its final recommendations on March 17, 1983, various changes were proposed.^[30] In 1983, US 2 was truncated, removing the overlap with I-75,^[31] and in 1986, US 10 was similarly shortened to remove an overlap with I-75.^[32] US 33 was all but eliminated in the state in 1986 as well, eliminating its overlap with US 31.^[33] Over a decade later, two highway designations were completely removed from the state in 1990s when US 33 and US 27 were truncated to end in Indiana in 1997^[34] and 1999,^[35] respectively. The latter also removed an overlap with I-69.^[36]

Additional freeway sections opened around the turn of the 21st century. The St. Johns Bypass along then-US 27 opened on August 31, 1998;^[37] and bypasses of Cadillac and Manton on US 131 opened in 2001^[38] and 2003.^[39] A 9.5-mile (15.3 km) freeway segment of US 31 north from Berrien Springs to Napier Avenue also opened in 2003.^[40][41] Plans still had support to convert the expressway segment of US 127 between Ithaca and St. Johns into a full freeway as of 2009.^[42] MDOT completed a re-evaluation of the environmental studies for the conversion, but future activities were limited to right-of-way acquisition without any commitments for actual construction.^[43] Plans are also still in place to complete the rest of the US 31 freeway near Benton Harbor,^[44] but funding has not been available.^[45]

More information Number, Length (mi) ...

Number	Length (mi)[1]	Length (km)	Southern or western terminus	Northern or eastern terminus	Formed	Removed	Notes
US 2	109.177	175.703	US 2 at Ironwood	US 2/US 141 at Mastodon Township south of Crystal Falls	01926-11-111926[3]	current	Western segment
US 2	195.974	315.390	US 2/US 141 at Breitung Township near Iron Mountain	I-75 and BL I-75 in St. Ignace	01926-11-111926[3]	current	Eastern segment
US 8	2.322	3.737	US 8 at Norway Township	US 2 in Norway	01926-11-111926[3]	current	Shortest US Highway in Michigan
US 10	139.656	224.755	Car ferry docks in Ludington	I-75/US 23 and BS I-75/M-25 in Monitor Township near Bay City	01926-11-111926[3]	current	Connects to US 10 in Wisconsin via the SS Badger car ferry
US 12	210.077	338.086	US 12 at New Buffalo Township	Michigan and Cass avenues in Detroit	01926-11-111926[3]	current	Michigan Avenue
US 16	210.643	338.997	Car ferry docks in Muskegon	US 10, US 12, US 25 and US 112 in Detroit	01926-11-111926[3]	01962-02-011962[23]	Replaced by I-96
US 23	362.152	582.827	US 23/US 223 at Whiteford Township near Temperance	I-75 in Mackinaw City	01926-11-111926[3]	current	Longest US Highway in Michigan
US 24	79.828	128.471	US 24 at Bedford Township near Erie	I-75 in Springfield Township near Clarkston	01926-11-111926[3]	current	Telegraph Road
US 25	190.953	307.309	US 25 at Erie Township	M-25 and M-53 in Port Austin	01926-11-111926[3]	01973-01-011973[24]	Replaced by M-125, I-75, M-3, I-94, and M-25[24]
US 27	218.195	351.151	I-69/US 27 at Kinderhook Township	I-75 in Beaver Creek Township near Grayling	01926-11-111926[3]	01999-04-161999[35]	Replaced by I-69 and US 127; signage removed in 2002[46]
US 31	355.179	571.605	US 31 at Bertrand Township near Niles	I-75 in Mackinaw Township near Mackinaw City	01926-11-111926[3]	current
US 33	2.835	4.562	US 33 at Milton Township	US 12 in Milton Township south of Niles	01938-01-011938[47]	01997-04-251997[34]	Replaced by M-51; signage removed in 1998[48]
US 41	278.769	448.635	US 41 at Menominee	Cul-de-sac at Fort Wilkins State Park near Copper Harbor	01926-11-111926[3]	current
US 45	54.759	88.126	US 45/WIS 32 at Watersmeet Township	Ontonagon and River streets in Ontonagon	01935-01-01c. 1935[49]	current
US 102	44.094	70.962	US 2 in Crystal Falls	US 41/M-28 in Covington Township	01926-11-111926[3]	01928-11-121928[11]	Replaced by US 141
US 112	205.507	330.731	US 12 in New Buffalo Township	US 10, US 12, US 16 and US 25 in Detroit	01926-11-111926[3]	01962-01-011962[22]	Replaced by US 12 when I-94 replaced US 12
US 112S	1.709	2.750	US 112S at Mason Township	US 112 in Mason Township near Adamsville	01933-01-011933[13]	01935-01-011935[12]	Replaced by M-205, now a county road
US 127	212.168	341.451	US 127 at the Wright–Medina township line near Waldron	I-75 in Beaver Creek Township near Grayling	01926-11-111926[3]	current
US 131	269.313	433.417	US 131 at Mottville Township near White Pigeon	US 31 in Petoskey	01926-11-111926[3]	current
US 141	7.892	12.701	US 141 at Quinnesec	US 2/US 141 in Breitung Township near Iron Mountain	01928-11-121928[11]	current	Southern segment
US 141	43.602	70.171	US 2/US 141 at Mastodon Township south of Crystal Falls	US 41/M-28 in Covington Township	01928-11-121928[11]	current	Northern segment
US 223	45.695	73.539	US 23/US 223 at Whiteford Township near Temperance	US 127 in Woodstock Township near Somerset	01930-01-011930[50]	current
Former

Close

• Mainline US Highways
• US 2 along Lake Michigan near Brevort
• Eastern terminus of US 8 in Norway
• The SS Badger connects US 10 in Ludington to Manitowoc, Wisconsin, across Lake Michigan.
• Iron Brigade Memorial Highway sign along US 12 in Pittsfield Township
• I-75/US 23 approaching the Zilwaukee Bridge
• US 24 (Telegraph Road) approaching the Mixing Bowl interchange in Southfield
• US 25 (Gratiot Avenue) in Detroit in 1941
• US 27 near Clare before conversion to a freeway
• US 31 freeway near Rothbury
• US 41 mileage sign in Copper Harbor showing the mileage to Miami, Florida
• US 45 entering Paulding
• US 127 through East Lansing
• Cloverleaf interchange between US 131 and M-6 near Wyoming
• Northern terminus of US 141 near Covington
• US 23/US 223 in Monroe County

• Michigan Highways portal