Mo. Rev. Stat. § 300.175: Display of unauthorized signs, signals or markings.

No person shall place, maintain or display upon or in view of any highway an 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.