M-86 is an east–west state trunkline highway in the US state of Michigan in the southern portion of the Lower Peninsula. The highway starts at Business US Highway 131 (Bus. US 131) and M-60 in Three Rivers and ends at US Highway 12 (US 12) near Coldwater. In between, it crosses farm country and runs along a section of the Prairie River. Following a highway originally numbered M-7, the roadway was renumbered M-86 in 1940. It has been a part of the state highway system at least since 1927. Two other roadways carried the M-86 designation in the 1920s. Two bridges along the road are eligible for inclusion on the National Register of Historic Places (NRHP). Route description M-86 begins in Three Rivers at a junction with Bus. US 131 and M-60. From there the road travels south out of town on Main Street and across the St. Joseph River. After crossing the river, the highway runs through a residential area of town and turns eastward into rural farm lands. M-86 crosses the Prairie River and follows Burr Oak Street into the community of Centreville. The highway switches to follow Main Street through downtown Centreville; east of downtown, Main Street curves along a bend in the river, and it runs parallel to the river out of town. As part of its support of the state highway system, the Michigan Department of Transportation (MDOT) tracks the traffic levels along the roads it maintains. These traffic counts are expressed in terms of average annual daily traffic (AADT), a calculation of the vehicles using a segment of roadway on a typical day of the year. In 2009, MDOT measured 7,642 vehicles including 138 trucks along M-86 in Centreville, the highest traffic levels along the whole highway. As the highway leaves town, it passes by the north side of Lake Templene, and Sand Lake near Nottawa before meeting M-66. From the junction, M-86 and M-66 run concurrently to the north for about , at which point M-86 branches off to the east while M-66 continues on a northerly route. M-86 continues east through agricultural land into the village of Colon. The highway follows South Street and turns north on Blackstone Avenue between Sturgeon and Palmer lakes. Turning to follow State Street, the trunkline heads out of the village to the southeast. It continues eastward along Colon Road, passing north of Matteson Lake near Matteson