Michigan Highway 120 is a fairly short route in west-central Michigan, extending northeasterly out of Muskegon. The southwestern end occurs at a unique at-grade interchange with the Business Route for US Route 31, on the north side of Muskegon. Michigan Highway 120 sets out northeasterly from there, encountering an interchange with the main freeway alignment of US Route 31. After passing through Twin Lake and Holton, it turns straight northerly, intersection Michigan Highway 82 near Fremont. Seven miles north of that junction, Michigan Highway 120 ends at Michigan Highway 20 in Hesperia. I don't know if Michigan Highway 120 was named after Michigan Highway 20, in the stylings of the Interstate Highway System's numbering scheme, or if the similarity of the two routes' numbers is a complete coincidence.
My photo of signage for Michigan Highway 120 shows the northern end marker in Hesperia. Travelers moving northward on Michigan Highway 120 will see this sign assembly as they approach the intersection with Michigan Highway 20 in this small town. This photo was taken on a trip to Grand Rapids and Ludington in July 2023.