In 1803, despite his doubts about the constitutionality of the power of Congress to buy land, President Jefferson made the purchase of Louisiana to France, doubling the size of the United States. The land acquired in this way amounted to 23% of the United States today, of about 810,000 ml², comprised the current states of Arkansas, Missouri, Iowa, the Minnesota area east of the Mississippi River, North Dakota, Dakota of the South, Nebraska, Oklahoma, most of Kansas, zones of Montana, Wyoming, the territory of Colorado to the east of the Rocky Mountains and the one of Luisiana to the east of the Mississippi river, with the city of New Orleans included.
The region of Louisiana was occupied by France at the beginning of the 18th century. In 1763, the Treaty of Paris, which ended the Seven Years' War, established that the eastern part of the Mississippi was ceded to Great Britain, while ratifying the Treaty of Fontainebleau by which France ceded the rest of Louisiana to Spain in compensation for the loss of Florida. In 1800 this territory returned to French sovereignty by the third Treaty of San Ildefonso. In 1802, however, there were two events that President Thomas Jefferson considered hostile to the interests of the United States: the sending of French troops to New Orleans and the island of Santo Domingo to suppress uprisings that had broken out in those territories, and the abolition of the right of deposit, privilege agreed with the American merchants in the past to store goods in New Orleans until their transshipment. Jefferson sent James Monroe to Paris to collaborate with the plenipotentiary minister in France, Robert R. Livingston, in the attempt to carry out one of the following four possibilities: the purchase of eastern and western Florida and New Orleans; the acquisition only of New Orleans; or the purchase of the territory on the banks of the Mississippi River to build a US port or the acquisition in perpetuity of navigation and storage rights.
The previous negotiations between Livingston and the French Minister of Foreign Affairs, Charles Maurice de Talleyrand-Perigord, failed. Later the international situation worsened for France. The French army of Santo Domingo was decimated by an epidemic of yellow fever and an uprising broke out on the island. Napoleon, determined to make the most of such a complicated situation, gave new instructions to Talleyrand, and on April 11, 1803, he surprised Monroe and Livingston with a single, non-negotiable offer: the purchase of Louisiana as a whole. Although this operation exceeded their powers, the US ambassadors accepted. At the beginning of May, three documents were signed by which France ceded Louisiana to the United States. The agreed price was of 15 million dollars, of which 11,250,000 supposed the payment to France of the rights of cession of the territories. The remaining $ 3,750,000 were used by the United States government to satisfy the claims of its citizens against France.
At the time of the purchase, Jefferson was questioned about the constitutionality of the acquisition of territories for not adding a new amendment to the US Constitution that would give him legal coverage. However, the acquisition of Louisiana was ratified by the United States Senate in the form of a treaty.
