R.I. Gen. Laws § 31-24-7: Tail lamps required.

Every motor vehicle, trailer, semi-trailer, and pole trailer, and any other vehicle which is being drawn at the end of a train of vehicles, shall be equipped with at least one tail lamp mounted on the rear, which when lighted as required in this chapter, shall emit a red light plainly visible from a distance of five hundred feet (500′) to the rear, provided that in the case of a train of vehicles only the tail lamp on the rearmost vehicle need actually be seen from the distance specified. Violations of this section are subject to fines enumerated in § 31-41.1-4.