As M-37 crosses into Lake County, the highway crosses the Pere Marquette River. US 10 follows M-37 through Baldwin. The Marquette Rail line turns westward on the edge of town, and north of Baldwin, the highway forms the dividing line between the Manistee National Forest to the west and the Pere Marquette State Forest to the east. The road crosses the Little Manistee River near Peacock and the Pine River in southwest Wexford County. M-37 curves to the northeast along the edge of the Hodenpyl Dam Pond near Mesick. M-37 turns east to follow M-115 through the community and then returns to a northward course into Sherman and on to Buckley. North of the latter community, the highway crosses into Grand Traverse County. The area around Buckley transitions to agricultural use again. This landscape continues past the M-113 to the area known as Chums Corners. 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.