- Southern Terminus:
- Commodore Perry Highway (US 1) in South Kingstown
- Northern Terminus:
- Post Road (US 1) in North Kingstown
RI 1A is a local alternative to US 1 between South Kingstown and North Kingstown. It is one of three routes in the state that carry the RI 1A designation. It is designated a scenic route and has special green route shields with the word "Scenic" at the top. It begins at US 1 and runs east along Post Road, changing names after a short distance to become Main Street. It then turns south and is multiplexed with RI 108 along Kingstown Road. After a few blocks, there is a rotary and RI 108 splits off to continue south as Point Judith Road. Kingstown Road turns to the east, changing names after a short distance to become Narragansett Avenue, which ends at Boston Neck Road in Narragansett. RI 1A turns north onto Boston Neck Road, which it follows to North Kingstown. There, Boston Neck Road curves to the west to become Phillips Street (RI 102). RI 1A turns north onto Brown Street for a few blocks and then west onto West Main Street to end at US 1.