US 1 is a divided highway for most of its length in this region; there is also a short freeway section in South Kingstown and Narragansett.

[1][2] Beginning in downtown Westerly, the roadway takes a more southerly route for its first 3.7 miles (6.0 km) in the town, serving the affluent coastal community of Watch Hill and Misquamicut State Beach.

Route 1A north continues southward on Beach Street before turning south onto Watch Hill Road.

[3] This segment is 1.4 miles (2 km) in length, begins shortly after Post Road passes Ninigret Pond in Charlestown.

[1][6] After traveling north for 2.7 miles (4.3 km) on US 1, the fourth section of Route 1A begins, again following Post Road.

After crossing US 1 via a median u-turn, Route 1A continues north for 16.5 miles (26.6 km), this time taking a more distant course from US 1.

This segment runs for 17.2 miles (27.7 km) and serves as a major commercial corridor for the towns of South Kinsgtown, Narragansett, and North Kingstown.

[1] Route 1A runs north and east along Post Road and Main Street into the village of Wakefield, a major commercial center of South Kingstown.

Route 1A serves as a major commercial corridor in northern Narragansett, and also provides access to the village of Bonnet Shores.

It then crosses into the Saunderstown neighborhood of North Kingstown, interchanging with Rhode Island Route 138 just west of the Jamestown-Verrazano Bridge.