Highway 126 begins at an intersection with Highway 81 in the Town of Elk Grove. From here, the highway heads north through farmland. It meets the western terminus of County Highway F before continuing north toward Belmont. At the village's southern edge, the highway curves to the east, following County Highway G. The road turns north at a junction with County Highway XX and heads through a residential area of Belmont as Mound Avenue. It continues north through the village's downtown, crossing the Pecatonica State Trail and a creek. From here, Highway 126 heads to the northwest as 1st Capitol Avenue, where it terminates at Exit 26 of US 151. The road continues northwest as County Highway G.[2][3]