M-66 is a north–south state trunkline highway on the Lower Peninsula 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 Lower Peninsula. 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-46 is an east–west state trunkline highway in the US state of Michigan between Muskegon and Port Sanilac, terminating near Lake Michigan and Lake Huron on each end. Except for the north–south segment that corresponds with the US Highway 131 (US 131) freeway between Cedar Springs and Howard City, M-46 is practically a due east–west surface highway. The road runs through rural sections of the Lower Peninsula connecting several freeways including US 31, US 131, US 127 and Interstate 75 (I-75).
M-76 is a former state trunkline highway designation in the Lower Peninsula of the US state of Michigan. The highway's designation was decommissioned when the last section of it was converted to freeway as a part of the present-day Interstate 75 (I-75). At that time, M-76 extended from US Highway 23 (US 23) near Standish northwesterly to I-75 south of Grayling. Two sections of the route followed freeways with a two-lane highway in between to connect them. The former routing of M-76 through West Branch before that city was bypassed was initially redesignated Business M-76. The highway itself ran through mixed fields and forests bypassing several other towns in the region.
M-33 is a north–south state trunkline highway in the US state of Michigan that runs from Interstate 75 (I-75) at Alger in Arenac County north to M-27 near Cheboygan. In between, the trunkline runs through rural sections of the northeastern Lower Peninsula including state and national forest areas. M-33 connects to a handful of parks and crosses several of the rivers in that section of the state. It runs concurrently with three other state highways, sharing pavement to connect through several small communities of Northern Michigan.
M-20 is a state trunkline highway in the US state of Michigan that runs from New Era to Midland. It crosses through rural Lower Peninsula forest land between the two ends. The highway serves the college towns of Big Rapids and Mt. Pleasant, home of the main campuses of Ferris State University and Central Michigan University, both located near the trunkline.
M-115 is a state trunkline highway in the northwestern part of the Lower Peninsula of the US state of Michigan. The highway takes a generally southeast-to-northwest direction between Frankfort on Lake Michigan and Clare in the central part of the state. The northwestern end is at M-22 next to Betsie Lake; the southeastern end in downtown Clare is at an intersection with Business US Highway 127 and Bus. US 10. In between, the trunkline runs about 96+1⁄2 miles (155.3 km) through woodlands, including areas that are a part of either the Manistee National Forest or the Pere Marquette State Forest. The highway also passes agricultural areas, several lakes in the region and a state park near Cadillac.
M-85, also known as Fort Street or Fort Road for its entire length, is a state trunkline highway in the U.S. state of Michigan. The highway serves several Downriver suburbs of Detroit, as well as neighborhoods in the city itself. From its southern terminus at exit 28 on Interstate 75 (I-75) to its second interchange with exit 43 on I-75 in southwest Detroit, M-85 is part of the Lake Erie Circle Tour. In between, it serves mostly residential areas running parallel to a pair of rail lines; the highway carries between 5,000 and 43,000 vehicles per day on average. Once in the city of Detroit, Fort Street runs parallel to I-75 for several miles before they separate near the Ambassador Bridge. The northern end of M-85 is at the intersection with Griswold Street in downtown Detroit, one block away from Campus Martius Park.
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-18 is a north–south state trunkline highway in the Lower Peninsula of the US state of Michigan. It runs for 77.530 miles (124.772 km) through the central region of the state connecting US Highway 10 (US 10) near North Bradley with M-72 in rural Crawford County near the community of Luzerne. In between, the roadway connects several smaller communities while running through woodlands in both state and national forest areas. Two segments of M-18 run along sections of county boundaries, and one part of the highway forms a component of the business loop for the village of Roscommon.
M-65 is a 103.176-mile-long (166.046 km) state trunkline highway in the US state of Michigan. The highway runs between termini on US Highway 23 (US 23) near Omer and Rogers City in the northeastern Lower Peninsula of the state. M-65 runs inland through several small communities in the region, passing through forests and fields along its course. M-65 crosses several watercourses, including the Au Sable River where it runs along the River Road National Scenic Byway. The region also includes the Huron National Forest and the Mackinaw State Forest areas.
US Highway 31 (US 31) is a part of the United States Numbered Highway System that runs from Alabama to the Lower Peninsula of the US state of Michigan. In Michigan, it is a state trunkline highway that runs from the Indiana–Michigan state line at Bertrand Township north to its terminus at Interstate 75 (I-75) south of Mackinaw City. Along its 355.2-mile-long (571.6 km) route, US 31 follows the Michigan section of the St. Joseph Valley Parkway as well as other freeways and divided highways northward to Ludington. North of there, the trunkline is a rural undivided highway through the Northern Michigan tourist destinations of Traverse City and Petoskey before terminating south of Mackinaw City. Along its route, US 31 has been dedicated in memory of a few different organizations, and sections of it carry the Lake Michigan Circle Tour (LMCT) moniker. Four bridges used by the highway have been recognized for their historic character as well.
US Highway 23 (US 23) is a north–south United States Numbered Highway that runs from Jacksonville, Florida, to Mackinaw City, Michigan. In the US state of Michigan, it is a major, 362-mile-long (583 km), north–south state trunkline highway that runs through the Lower Peninsula. The trunkline is a freeway from the Michigan–Ohio state line near Lambertville to the city of Standish, and it follows the Lake Huron shoreline from there to its northern terminus. Serving the cities of Ann Arbor and Flint, US 23 acts as a freeway bypass of the Metro Detroit area. Overall, the highway runs through rural areas of the state dominated by farm fields or woodlands; some segments are urban in character in the Ann Arbor, Flint and Tri-Cities areas. The section from Flint north to Standish also carries Interstate 75 (I-75) along a concurrency that includes a segment that carries almost 70,000 vehicles on a daily basis.
There are six business routes of US Highway 131 in the state of Michigan, and previously there was one bypass route and an additional business route. All of the business routes are former sections of US Highway 131 (US 131). These former sections of the mainline highway, along with the necessary connecting roads, allow traffic to access the downtowns business districts of cities bypassed by sections of US 131 built since the 1950s. The extant business loops connect to Constantine, Three Rivers, Kalamazoo, Big Rapids, Cadillac, and Manton. The former bypass route in Grand Rapids allowed traffic to bypass that city's downtown at a time when US 131 still ran through the heart of the city, and the later business route connected through downtown while US 131 ran on a freeway bypassing the central business district.
There have been nine business routes for Interstate 75 in the US state of Michigan. Numbered either Business Loop Interstate 75 or Business Spur Interstate 75 depending if they are a full business loop or a business spur, these highways are former routings of I-75's predecessor highways in the state. They were designated as I-75 was completed through the various areas of Michigan. The business loop in Pontiac runs through that city's downtown along a section of Woodward Avenue and a segment of roadway formerly used by M-24. The former Saginaw business loop was once a part of US Highway 23 (US 23), as was most of the original Bay City business loop. The roadways that make up the business loops in West Branch and Roscommon were previously part of M-76, I-75's predecessor through that part of the state. In Northern Michigan, the Grayling and Gaylord BL I-75s were part of US 27, and the two business routes in St. Ignace and Sault Ste. Marie in the Upper Peninsula of Michigan were part of US 2. A tenth business route, a loop through Indian River has been proposed. Each of the business loops connects to I-75 on both ends and runs through their respective cities' downtown areas. The two business spurs only connect to I-75 on one end and run into the appropriate downtown.
US Highway 10 (US 10) is a part of the United States Numbered Highway System that runs from West Fargo, North Dakota, to the Lower Peninsula of the US state of Michigan. The highway enters Michigan on SS Badger, which crosses Lake Michigan between Manitowoc, Wisconsin, and Ludington. As the highway crosses the state, it is a two-lane undivided highway between Ludington and Farwell and a freeway from Farwell east to the highway's terminus in Bay City. US 10 runs concurrently with US 127 in the Clare area along a section of freeway that includes a welcome center in the median. Outside of the Clare and Midland areas, US 10 runs through rural areas of West and Central Michigan in a section of the Manistee National Forest as well as farmfields.
US Highway 127 (US 127) is a part of the United States Numbered Highway System that runs from Chattanooga, Tennessee, to the Lower Peninsula of Michigan. In Michigan, it is a state trunkline highway that runs for 212.2 miles (341.5 km), entering from Ohio south of Hudson and ending at a partial interchange with Interstate 75 (I-75) south of Grayling. US 127 is the primary route connecting Lansing and Central Michigan to Northern Michigan and the Mackinac Bridge. From the south side of Jackson northerly, it is mostly a four-lane freeway. A notable exception is a 16-mile (26 km) stretch from north of St. Johns to just south of Ithaca, where the highway is built as an expressway and speed limits are lower. South of Jackson to the state line, the trunkline is a two-lane, undivided highway with access from adjacent properties.
US 31 near Manistee 
US 23 in Tawas City 
