It follows the East Boyer River through Denison as the Boyer River forks west of the northern intersection with US 59 / Iowa 141. US 30 travels north-northeasterly towards Vail.
As the East Boyer River flows through Denison, it bifurcates west of the northern point where US 59 / Iowa 141 intersects. At the same time, US 30 moves north-northeasterly toward Vail.