It begins on the west side of Hot Springs at an intersection with US 18 and travels in a southeasterly direction.

begins at a diamond interchange with Interstate 35 (I-35) on the eastern edge of Clear Lake, Iowa.

The route, overlapped by Iowa Highway 122 (Iowa 122), begins as a four-lane divided highway, serving the Mason City Municipal Airport before entering Mason City proper.

At Jefferson Avenue, US 18 Bus./Iowa 122 separate into a pair of one-way streets, remaining in this configuration through the downtown area where the Park Inn Hotel, one of Frank Lloyd Wright's few commercial buildings, resides.

The business loop rejoins its parent route south of the city limits.

The route descends into the Mississippi River valley along the northern border of Pikes Peak State Park and then turns into McGregor.

travels a narrow strip of land between the river and the bluffs where it passes a riverboat casino.

ends at the foot of the Marquette–Joliet Bridge, which carries US 18 to Prairie du Chien, Wisconsin.

From there, the business routes run east-northeast as a four-lane divided highway until the intersection with Legion Street, where it becomes a local two-lane undivided road.

At the intersection with North and South Main streets (CTH-M), West Verona Avenue becomes East Verona Avenue, making a brief reverse curve to the left before returning to its previous trajectory at School Street and becoming a four-lane divided highway east of there.

US 151/CTH-MV ends east of Verona at exit 81 on US 18/US 151, but only with an eastbound onramp and westbound offramp.