It continues north past the locally famous "Mile Long Bridge", which carries the highway across Lake Red Rock, and then intersects Iowa 163 in Monroe.

It proceeds north to Newton, where it intersects Interstate 80 and a short overlap with US 6 begins.

It continues north through Laurel, then intersects US 30 at the southern edge of Marshalltown.

It continues north until Iowa 3, with which it overlaps for one mile (1.6 km) near Allison.

It continues north west of Allison through Greene, goes through Roseville, then turns east towards Charles City.