The birthday of Thomas Jefferson, who was the United States' third president, is an annual national legal observance on April 13. He was the principal author of the U.S. Declaration of Independence and is known as one of the country's founding fathers. Presidents' Day also honors Jefferson, fellow president George Washington, and other U.S. presidents. Get access to all Thomas Jefferson's birthday, Thomas Jefferson birthplace, Thomas Jefferson's birthday and death, Thomas Jefferson death date, Thomas Jefferson place of birth.