There are no copyright markings pertaining to the image as can be seen in the links above. At bottom is Country of origin USA, a logo for the Morgan Litho Company of Cleveland, Ohio--they printed the poster--and a number M-12070. The number seems to be related to the print job for 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 Phantom of the West''. |Source=[http://cinemasterpieces.com/62014/phanaug14.jpg source] |Date=[http://www.imdb.com/title/tt0021249/ 1931] |Author=Mascot Pictures |Permission=Pre-1978 no mark |ot...