Today is Thomas Jefferson's Birthday. Thomas Jefferson (April 13, 1743 - July 4, 1826) was an American Founding Father, the principal author of the United States Declaration of Independence (1776) and the third President of the United States (1801-1809). He was the first United States Secretary of State (1790-1793). As Vice-President opposed to John Adams, Jefferson with Madison secretly wrote the Kentucky and Virginia Resolution, which attempted to nullify the Alien and Sedition Acts and formed the basis of states rights. Elected president in 1800, he oversaw a peaceful transition in power, purchased the vast Louisiana Territory from France (1803), and sent the Lewis and Clark Expedition (1804-1806) to explore the new west. On July 4th, 1826 at ten minutes before one o'clock Jefferson died at the age of 83 , the fiftieth anniversary of the Declaration of Independence.