The United States, afraid that France might withdraw its offer if they failed to act quickly, signed the Louisiana Purchase Treaty with France on April 30, 1803. News of the treaty reached Washington, D.C. and was announced to the American people on July 4th of that year. The purchase was at first controversial, with many Americans fearing that Jefferson had acted unconstitutionally. Additionally, some people, especially within the Spanish government, argued that France had not had the right to sell the territory. Nevertheless, Spain ceded Louisiana to France on November 30, 1803, and France gave the territory to the United States on December 30, 1803.
Louisiana Purchase Treaty, April 30, 1803. General Records of the U.S. Government, Record Group 11, National Archives.