The southern terminus is near the border between Kalamazoo and Calhoun counties at exit 92 of Interstate 94 (I-94) southwest of Battle Creek.

M-37 runs for 221.27 miles (356.10 km) through the western side of the Lower Peninsula of Michigan connecting Battle Creek, Grand Rapids and Traverse City.

[8] M-37 starts joined with Business Loop I-94 (BL I-94) as the two highway designations run concurrently at exit 92 on I-94 southwest of Battle Creek.

When the roadway meets M-96, BL I-94/M-37 turns northward, joining M-96 around the eastern end of the airport to Dickman Road.

West of Hastings, M-43 separates and heads south toward Kalamazoo while M-37 turns northwesterly and runs parallel to the Thornapple River.

The highway follows the river west and north to the community of Middleville through mixed farms and forests.

North of 76th Street, Broadmoor widens to a four-lane boulevard which passes a campus of Davenport University near the M-6 freeway on the outskirts of the Grand Rapids area.

This section is dominated by light industrial complexes west of the Gerald R. Ford International Airport in the suburb of Kentwood.

North of the malls, M-37 passes through the campus of Calvin University and along residential areas at the east end of Reeds Lake.

Near 3 Mile Road, I-96/M-37 runs west again, continuing across the Grand River and meeting the US Highway 131 (US 131) freeway.

This highway splits from Alpine Avenue north of 8 Mile Road and turns to the northwest as the surroundings transition to rural farmland again.

There, M-37 merges with US 31, and the two run through a small unincorporated community that is host to Turtle Creek Stadium, home of the Traverse City Pit Spitters, a minor league baseball team.

As the highway heads towards Grand Traverse Bay and downtown, it passes several car dealerships, an outlet mall and other retailers.

North of 14th Street, US 31/M-37 passes the former Traverse City State Hospital, a Kirkbride Plan former mental asylum.

When the two streets meet, M-22 ends, and US 31/M-37 and M-72 merge into a triple concurrency along the bay north of downtown Traverse City.

Grandview Parkway ends east of the mouth of the river, and the highway continues along Front Street past the Great Lakes Maritime Academy and the home berth of the TS State of Michigan to Garfield Avenue near the campus of Northwestern Michigan College.

[14] These trees are said to "explode in a filigree of creamy pink blossoms in May" by the editors of Reader's Digest magazine.

M-37 ends at a cul-de-sac in front of the building which is located near the 45th Parallel, halfway between the North Pole and the Equator.

[22] Construction progressed slowly and was only opened through Wexford County in 1863. and the bridge over the Manistee River in 1864 at what is now Sherman.

This section of highway ran from Battle Creek to Grand Rapids, roughly along the modern routing.

[25] A group of local leaders formed an organization to lobby for the completion of the highway in 1928 when state efforts to do stalled.

[26] An unnumbered section of gravel highway was opened in 1937 west of Cadillac; the roadway extended south from M-55 to the Wexford–Lake county line.

[29][30] The spur in Wexford County is shown after 1941 as an "earthen" highway,[31] before disappearing from state maps completely in 1945.

[36][37] In 1953, this routing was shifted further when M-37 was rerouted to run north on East Beltline Avenue concurrent with US 131 and M-21 to Cascade Road.

There it turned west along Cascade Road and Fulton Street into downtown back to its existing alignment.

[44][45] The final Grand Rapids routing change was made in 1969 when M-37 was moved to its current course along East Beltline Avenue and I-96.

[50] In 2008, the northernmost 18 miles (29 km) on the Old Mission Peninsula were designated what is now a Pure Michigan Scenic Byway by MDOT.

[51] To expand the blast radius for ammunitions testing at Fort Custer, MDOT rerouted the BL I-94/M-37 to run along the southern and eastern edges of the airport in Battle Creek instead of following roads on the opposite sides.

[55] If the change were completed, MDOT would have removed M-37 from the US 31 concurrency through Traverse City, truncating the highway to terminate in Chums Corners.