The current route starts at Business US 31 (Bus. US 31) where Muskegon Lake and the Muskegon River meet in Muskegon. As it crosses the river, it is known as the Veterans Memorial Causeway, with a section of Veterans Memorial Park between the northbound and southbound sections of the road. This road continues north as Whitehall Road, which connects Muskegon to Whitehall. At Whitehall Road, M-120 turns east on Holton Road and continues in a northeastern direction through the suburb of North Muskegon. The south side of the roadway abuts residential areas and Reeths-Puffer High School; the north side is largely undeveloped. M-120 meets the US 31 freeway in Muskegon Township. Holton Road continues northeasterly past Oak Hill Cemetery and turns northerly at Bard Road. The highway curves to the northeast again through Twin Lake to avoid several lakes in the area. The landscape along the road between Twin Lake and Holton, like much of the overall route of the highway, is woodland. Northeast of Holton, those forests transition to farm land as M-120 turns to the north. The highway meets B-31 as it turns north to run along the Muskegon–Newaygo county line.