M-37 is a north–south state trunkline highway in the US state of Michigan. The southern terminus is near the border between Kalamazoo and Calhoun counties at exit 92 of Interstate 94 (I-94) southwest of Battle Creek. The northern terminus is at the Mission Point Light on Old Mission Point in Grand Traverse County. In between, the highway connects Battle Creek, Grand Rapids and Traverse City. Motorists will travel through agricultural land, forests, suburbs and large cities along the way. The section of M-37 on the Old Mission Peninsula was designated what is now a Pure Michigan Scenic Byway in 2008.
M-60 is an east–west state trunkline highway in the US state of Michigan. It runs from the Niles area at a junction with US Highway 12 (US 12) to the Jackson area where it ends at Interstate 94 (I-94). The trunkline passes through a mix of farm fields and woodlands, crosses or runs along several rivers and connects several small towns of the southern area of the state. The westernmost segment runs along divided highway while the easternmost section is a full freeway bypass of Jackson.
M-66 is a north–south state trunkline highway on the Lower Peninsula (LP) of the US state of Michigan. It runs from the Indiana state line in the south to Charlevoix in the north. M-66 is the only state highway to run the north–south distance of the LP. It starts as a continuation of State Road 9 (SR 9) which provides access to the Indiana Toll Road. The total length is approximately 272.9 miles (439.2 km), which includes almost 3.4 miles (5.5 km) of freeway between Interstate 94 (I-94) and downtown Battle Creek designated as I-194. A section of the highway immediately south of I-94 is an expressway, a type of divided limited-access highway, while the section along I-194 is a full freeway; otherwise M-66 is a two-lane rural highway. Two sections are listed on the National Highway System.
M-78 is a state trunkline highway in the US state of Michigan. The western terminus is the intersection with M-66 north of Battle Creek in Pennfield Township. The roadway runs 10.744 miles (17.291 km) through rural farmland and the community of Bellevue as it approaches its eastern terminus at an interchange with Interstate 69 (I-69) near Olivet. The highway is used by between 3,100 and 5,300 vehicles on a daily basis.
M-89 is an east–west state trunkline highway in the US state of Michigan that runs from near Ganges to Battle Creek. M-89 starts at an interchange with Interstate 196/US Highway 31 (I-196/US 31) and passes through Allegan, Kalamazoo County, Michigan, and Calhoun counties. The highway also briefly crosses the southwest corner of Barry County before it terminates an at intersection with Business Loop I-94 on the northwestern side of downtown Battle Creek. In between the trunkline runs parallel to the Kalamazoo River through rural southwestern Michigan farmlands while also running through the middle of several smaller towns in the area.
Interstate 196 (I-196) is an auxiliary Interstate Highway that runs for 80.6 miles (129.7 km) in the US state of Michigan. It is a state trunkline highway that links Benton Harbor, South Haven, Holland, and Grand Rapids. In Kent, Ottawa, and Allegan counties, I-196 is known as the Gerald R. Ford Freeway, or simply the Ford Freeway, after President Gerald Ford, who was raised in Grand Rapids and served Michigan in the House of Representatives for 25 years. This name generally refers only to the section between Holland and Grand Rapids. I-196 changes direction; it is signed as a north–south highway from its southern terminus to the junction with US Highway 31 (US 31) just south of Holland, and as an east–west trunkline from this point to its eastern terminus at an interchange with I-96, its parent highway. There are three business routes related to the main freeway. There are two business loops and one business spur that serve South Haven, Holland and the Grand Rapids areas. Another business spur for Muskegon had been designated relative to the I-196 number.
M-99 is a north–south state trunkline highway in the Lower Peninsula of the US state of Michigan. It runs from the Ohio state border, where it connects to State Route 15 (SR 15), north to Lansing, where it terminates at a junction with Interstate 496 (I-496) and the Capitol Loop. The highway mainly serves local communities along the route as it passes through farm lands in the southern part of the state. One short segment, in Jonesville, is routed concurrently with US Highway 12 (US 12). The segment within Lansing follows Martin Luther King Jr. Boulevard.
M-43 is a state trunkline highway in the southwestern and central parts of the US state of Michigan. The highway runs from South Haven to Webberville along an indirect path through both rural areas and larger cities. The trunkline follows five overall segments: a southeasterly track from South Haven to Oshtemo Township, a northerly path to Plainwell, a southeasterly route to Richland, a northeasterly course to the Hastings area and an easterly route through the Lansing area.
M-79 is an east–west state trunkline highway in the central portion of Lower Peninsula of the U.S. state of Michigan. The western terminus is about three miles (4.8 km) southeast of Hastings at the junction with M-37 and the eastern terminus is in downtown Charlotte at the junction with M-50 and Business Loop Interstate 69 (BL I-69). It passes through Quimby and Nashville, where there is a junction with M-66. The entire highway is undivided surface road. It has no direct access with Interstate 69 (I-69), although a sign for the highway is located on southbound I-69 at exit 61.
M-59 is an east–west state trunkline highway that crosses the northern part of Metropolitan Detroit in the US state of Michigan. It runs between Howell at Interstate 96 (I-96) and I-94 on the Chesterfield–Harrison township line near the Selfridge Air National Guard Base. While primarily a multi-lane surface highway, it is a full freeway from just east of downtown Pontiac near Opdyke Road to just east of the Mound Road/Merrill Road exit in Utica. The various surface highway segments are named either Highland Road, Huron Street or Hall Road, with the latter known as an area for shopping and dining. The rural sections west of Pontiac pass through Oakland County lake country, passing through two state recreational areas.
M-11 is a state trunkline highway in the US state of Michigan in the Grand Rapids metropolitan area. The highway runs through the western and southern sides of the metro area, starting over the border in Ottawa County at an interchange with Interstate 96 (I-96). It runs through both rural woodlands and busy commercial areas before it terminates at another interchange with I-96 in Cascade Township. Locally known as Wilson Avenue and 28th Street, the trunkline is listed on the National Highway System. M-11 carries between 8,000 and 42,000 vehicles on average each day.
US Highway 27 (US 27) is a part of the US Highway System that now runs from Miami, Florida, to Fort Wayne, Indiana. In the US state of Michigan, it was a north–south state trunkline highway that entered the state south of Kinderhook and ended south of Grayling. Its route consisted of a freeway concurrency with Interstate 69 (I-69) from the state line north to the Lansing area before it followed its own freeway facility northward to St. Johns. From there north to Ithaca, US 27 was an expressway before continuing as a freeway to a terminus south of Grayling.
M-218 was a state trunkline highway in the US state of Michigan that served as a connector route from Interstate 96 in Wixom through Oakland County's lake country area to Business US 10 in Pontiac. M-218 was originally designated by 1936 and extended into Pontiac in 1938. The highway was decommissioned in 1963.
Interstate 94 (I-94) is a part of the Interstate Highway System that runs from Billings, Montana, to the Lower Peninsula of the US state of Michigan. In Michigan, it is a state trunkline highway that enters the state south of New Buffalo and runs eastward through several metropolitan areas in the southern section of the state. The highway serves Benton Harbor–St. Joseph near Lake Michigan before turning inland toward Kalamazoo and Battle Creek on the west side of the peninsula. Heading farther east, I-94 passes through rural areas in the middle of the southern Lower Peninsula, crossing I-69 in the process. I-94 then runs through Jackson, Ann Arbor, and portions of Metro Detroit, connecting Michigan's largest city to its main airport. Past the east side of Detroit, the Interstate angles northeasterly through farmlands in The Thumb to Port Huron, where the designation terminates on the Blue Water Bridge at the Canadian border.
US Highway 12 (US 12) is an east–west US Highway that runs from Aberdeen, Washington, to Detroit, Michigan. In Michigan it runs for 210 miles (338 km) between New Buffalo and Detroit as a state trunkline highway and Pure Michigan Byway. On its western end, the highway is mostly a two-lane road that runs through the southern tier of counties roughly parallel to the Indiana state line. It forms part of the Niles Bypass, a four-lane expressway south of Niles in the southwestern part of the state, and it runs concurrently with the Interstate 94 (I-94) freeway around the south side of Ypsilanti in the southeastern. In between Coldwater and the Ann Arbor area, the highway angles northeasterly and passes the Michigan International Speedway. East of Ypsilanti, US 12 follows a divided highway routing on Michigan Avenue into Detroit, where it terminates at an intersection with Cass Avenue.
There are currently eight business routes of Interstate 94 (I-94) in the US state of Michigan. These business routes connect I-94 to the downtown business districts of neighboring cities. Seven of the eight routes are business loops which bear the Business Loop I-94 designation while one is a business spur that bears the Business Spur I-94. These loops are former routings of I-94's two predecessors in Michigan: US Highway 12 (US 12) or US 25. The westernmost BL I-94 runs through the twin cities of Benton Harbor and St. Joseph along the former routing of US 12 and US 31/US 33 that now includes a section of the Lake Michigan Circle Tour in the state. The loops in Kalamazoo, Battle Creek, Marshall, Albion, and Jackson were also formerly segments of US 12 which were later designated as separate version of Business US Highway 12 through their respective cities before becoming BL I-94s in 1960. The BL I-94 in Kalamazoo was converted into BS I-94 in 2019. The route of the business loop through Ann Arbor was previously US 12 and then later M-14 before receiving its current moniker. The BL I-94 through Port Huron was previously US 25 and then Business US Highway 25.
There are currently four business routes of Interstate 69 (I-69) in the US state of Michigan. Designated Business Loop Interstate 69, they are all former routings of I-69's predecessor highways, US Highway 27 (US 27), M-78 or M-21, in whole or in part. The BL I-69 in Coldwater and the one in Charlotte were both parts of US 27 before the freeway bypassed those two cities in 1967 and the early 1970s, respectively. The BL I-69 through Lansing and East Lansing was previously part of M-78 and Temporary I-69 until it was redesignated in 1987. Before 1984, the loop in Port Huron was originally part of M-21 and was initially a business spur numbered Business Spur Interstate 69. It was later redesignated when it was extended to run concurrently with that city's BL I-94 which was originally part of I-94's predecessor, US 25. Each business loop follows streets through each city's downtown areas and connects to I-69 on both ends, giving traffic a route through the downtown and back to the freeway.
There have been six business routes of Interstate 96 (I-96) in the US state of Michigan. There are two business loops designated Business Loop Interstate 96 : one through Lansing and one through Howell. Both follow the old route of US Highway 16 (US 16), with appropriate connections to I-96. There are three former business spurs that were designated Business Spur Interstate 96. One connected to the carferry docks in Muskegon, running concurrently with part of Business US 31 along former US 16, but it has been eliminated. The second spur ran into downtown Portland until it was decommissioned in 2007. Two routes in the Detroit area—a loop through Farmington and a spur into Detroit—both using Grand River Avenue, and meeting at the temporary end of I-96 near Purdue Avenue, were eliminated when I-96 was moved to the completed Jeffries Freeway in 1977. The Farmington business route is still state-maintained as an unsigned highway, while the Detroit business route remained unsigned until it was decommissioned in 2016 and replaced by an extension of M-5.
There have been five different business routes of US Highway 23 in the state of Michigan. These business routes were designated along former sections of US Highway 23 (US 23) to provide signed access from the main highway to the downtowns of cities bypassed by new routings of US 23. Two are still extant, connecting through downtown Ann Arbor and Rogers City. Three others have been decommissioned. The former Business US 23 in Fenton was split in half during the 1970s and later completely turned back to local control in 2006. The former business loops through Saginaw and Bay City were renumbered as business loops of Interstate 75 in the 1960s.
BS I-94 at Kalamazoo 
I-69 / BL I-94 at Marshall 
