The Declaration of Independence was adopted in Philadephia.
Its author, Thomas Jefferson, was 33 years old.
John Hancock was 39.
George Walton, a signer from Georgia, was probably 27 (His birth month is not reflected in his bio).
Two signers from South Carolina, Thomas Lynch Jr. and Edward Rutledge, were only 26, and are said to be the youngest to sign the document.
While approved in Congress on July 4th, many of the signers didn't actually put their signatures to the document until the following month.