Staying close to the Atlantic Ocean and Narragansett Bay, it is a longer route than Interstate 95 (I-95), and many portions are a four-lane divided highway.

US 1 enters Rhode Island via a small bridge from Pawcatuck, Connecticut, to downtown Westerly.

The southbound side has junction with Prosser Trail, a road leading to Burlingame State Park.

Route 1A merges onto US 1 from the south, briefly, before exiting and continuing north to Cross Mills.

After northbound junctions with more beach access roads (Falcone Lane, Narrow Lane, which is split in half by the highway, the other half continuing on the southbound side that leads to South County Trail), US 1 continues into South Kingstown, where Green Hill Beach Road (Route 1A) meets US 1 on the northbound side and Post Road (also Route 1A) meets US 1 south.

Following this is Succotash Road, which leads to Jerusalem, Snug Harbor, and East Matunuck State Beach.

The turnpike south of Providence—the Providence and Pawcatuck and Hopkinton and Richmond turnpikes—followed the diagonal route that I-95 now takes.