This signature is believed to be ineligible for copyright and therefore in the public domain because it falls below the required level of originality for copyright protection both in the United States and in the source country (if different). In this case, the source country (e.g. the country of nationality of the signatory) is believed to be United States of America.
Note that this tag cannot be used on all signatures, as not all signatures are copyright-free.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
Uploaded a work by unknown photographer, book editor was Winfield Scott Downs (1895-1958) from {{cite book | editor-last=Downs |editor-first=Winfield Scott |title=Encyclopedia of American Biography: New Series |volume=12 | publisher=American Historical Society |year=1941 | pages=xx-yy | oclc=649569887 | url=https://babel.hathitrust.org/cgi/pt?id=wu.89080535578&view=1up&seq=542 }} with UploadWizard