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.
This photo published before 1946 is in the public domain in Trinidad and Tobago because the Copyright Act 1985 had a term of 50 years after publication for photographs.
Note: The Copyright Act 1997 and its amendments were not retroactive: "This Act shall also apply to works made, performances given, sound recordings made and broadcasts first transmitted before the date of the coming into force of this Act, provided that the term of protection had not expired under the Copyright Act, 1985"
Captions
Pan American Flight 161 crash 1945 in the waters off of Port of Spain