Display of any likeness of the US Presidential Seal is restricted by US Federal law under 18 USC 713; however, use in encyclopedias "incident to a description or history of seals, coats of arms, heraldry, or the Presidency or Vice Presidency" is allowed under Executive Order 11649.
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.
This image shows a flag, a coat of arms, a seal or some other official insignia. The use of such symbols is restricted in many countries. These restrictions are independent of the copyright status.
Captions
Seal of the President of the United States of America.