There are no copyright marks. At bottom left is Country of origin USA. Also at bottom is Morgan Litho Corp. Cleveland, O.-they printed the poster-and 3SH (for 3 sheet poster} looks like Rep (for Republic) 10660.
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 (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
{{Information |Description=Poster for the 1937 film ''The Gambling Terror''. |Source=[https://movieposters.ha.com/itm/western/the-gambling-terror-republic-1937-three-sheet-4125-x-8025-western/a/161610-51159.s?ic4=GalleryView-Thumbnail-071515 source] |D...