R.I. Gen. Laws § 5-18-2: Regulatory powers of town and city councils.

In order to preserve the health, safety, morals, and comfort of the inhabitants of this state, the city and town councils, in addition to any powers now enabling, shall have power by ordinance to regulate outdoor advertising in their city or town, as to the place where that advertising may be permitted; the size and kind of the structures upon which it may be placed; and the subject matter that may appear on the outdoor advertising; provided, that those regulations are reasonable in their requirements.