Route 4 begins at a fork in the alignment of U.S. Route 1 in the community of North Kingstown; the two left lanes of US 1 default onto Route 4 north, with the right-hand lane carrying Tower Hill Road and US 1 north into the village of Wickford.
Shortly after the intersection with Oak Hill Road, Route 4 transitions from a divided arterial highway into a four-lane limited-access freeway.