The item has no copyright markings on it as can be seen in the links above. At bottom left is Litho in USA and some numbers which apparently relate to the print job of the poster. At lower right is Tooker Litho Co., NY, a "D" (poster version D) and some numbers which probably relate to the printing of the poster,
This work is in the public domain in the United States because it was published in the United States between 1929 and 1977, inclusive, without a copyright notice. For further explanation, see Commons:Hirtle chart as well as a detailed definition of "publication" for public art. 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.