Pre-1978 no mark. There are no copyright marks. At bottom left is Coubtry of origin USA 8216. At bottom right is Morgan Litho Co Cleveland, O. 15249-they printed the poster.
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 1931 film ''The Nevada Buckaroo''. |Source=[https://movieposters.ha.com/itm/western/the-nevada-buckaroo-tiffany-1931-one-sheet-275-x-41-/a/7113-86602.s?ic4=GalleryView-Thumbnail-071515# source] |Date=[http://ww...