The name Green River Ordinance is given to a common American city ordinance prohibiting door-to-door solicitation. Under such an ordinance, it is illegal for any business to sell their items door-to-door without express permission from the household beforehand. Some versions prohibit all organizations, including non-profit charitable, political, and religious groups, from soliciting or canvassing any household that makes it clear, in writing, that it does not want such solicitations (generally with a "No Trespassing" or "No Solicitations" sign posted.)