No known copyright for Curt Teich postcards printed before 1964, with the following exception: if the Teich postcard has a photographer's copyright on it, or depicts a trademarked image, the user must seek permission from any holders of rights. For ease in dating Curt Teich postcards there is a dating guide available: link
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.