1803: The Senate ratified the Louisiana Purchase Treaty by a vote of 24 to seven. The agreement, which provided for the purchase of the western half of the Mississippi River basin from France at a price of $15 million, or approximately four cents per acre, doubled the size of the country and paved the way for westward expansion beyond the Mississippi. Spain had controlled Louisiana and the strategic port of New Orleans with a relatively free hand since 1762. President Thomas Jefferson feared that if Louisiana came under French control, American settlers living in the Mississippi River Valley would lose free access to the port of New Orleans. On April 18, 1802, Jefferson wrote a letter to Robert Livingston, the U.S. minister to France, warning that, "There is on the globe one single spot, the possessor of which is our natural and habitual enemy. It is New Orleans." (Source: Library of Congress)