Sites listed on the National Register of Historic Places may wish to display a commemorative plaque. The National Register of Historic Places does not issue plaques as a result of listing, however individual owners may choose to have one made and installed. There is not a required style or wording for plaques.
Many local trophy, plaque and monument companies produce these types of signs. If you do not have a local store that you prefer, Preservation Magazine provides a list of companies that produce plaques. The State Historic Preservation Offices does not endorse, authorize, recommend, or imply any connection to any one company over another, including any company not listed.