R.I. Gen. Laws § 31-13-10: Unauthorized signs and devices prohibited.

(a) No person shall place, maintain, or display upon or in view of any highway any unauthorized sign, signal, marking, or device which purports to be or is an imitation of or resembles an official traffic control device or railroad sign or signal, or which attempts to direct the movement of traffic, or which hides from view or interferes with the effectiveness of any official traffic control device or any railroad sign or signal, and no person shall place or maintain upon any highway any traffic sign or signal bearing on it any commercial advertising without the consent of the chief of police of the city or town in which the highway is located. This shall not be deemed to prohibit the erection upon private property adjacent to highways of signs giving useful directional information and of a type that cannot be mistaken for official signs.

(b) Every prohibited sign, signal, or marking is declared to be a public nuisance, and the authority having jurisdiction over the highway is empowered to remove it or cause it to be removed without notice.