The oldest person to sign the Constitution of the United States was Benjamin Franklin. When the document was signed on Sept. 17, 1787, Franklin was 81 years old.
Benjamin Franklin was far older than most of the other signers. The average age of the signers of the Constitution was 44. The youngest person to sign the Constitution was Jonathan Dayton of New Jersey, who was only 26 at the time. Owing to his advanced age and storied political career, Franklin became known as "the Sage of the Constitutional Convention." Franklin is credited with writing the Albany Plan of 1754, a document that preceded the Constitution and attempted to establish a national union.