President Thomas Jefferson was the third President of the United States, serving from 1801 to 1809. He is best known for drafting the Declaration of Independence in 1776, which proclaimed the colonies' freedom from British rule. Jefferson was a strong advocate for individual rights and democracy, believing in the importance of education and an informed citizenry. During his presidency, Jefferson completed the Louisiana Purchase in 1803, which doubled the size of the United States. He also commissioned the Lewis and Clark Expedition to explore the newly acquired territory. Jefferson's vision of an agrarian America shaped the nation's early development and values.