1762:

Treaty of Fontainebleau. France cedes New Orleans and her colony of Louisiana, west of the Mississippi River, to Spain, her ally in the recent Seven Years’ War against Britain. Hostilities in the war end the following year in the Treaty of Paris.

1769:

Spain takes control of Louisiana and New Orleans.

1783:

Treaty of Paris. Britain recognizes the independence of the United States, including America’s right of navigation on the Mississippi River.

1784:

Spain sees the expansion of the United States as an imminent threat to her properties in Louisiana, and closes the Mississippi River to navigation and the right of deposit in New Orleans. This action produces outrage among the Americans in the western settlements, and results in numerous confrontations on the Mississippi River between American frontiersmen and Spanish officials.

1789:

The French Revolution begins.

1793:

The French Revolution turns bloody with the execution of King Louis XVI, and those loyal to monarchy, by the revolutionaries; and then to war, when France declares war on England on February 1 and on Spain on March 7 in Europe, prompting the United States to declare its neutrality on April 23.

1795:

Because of European entanglements and war, again with Britain, Spain, which changed allies by deserting Britain in favor of France, is receptive to negotiations by Thomas Pinckney, the American Minister, and concedes free navigation of the Mississippi River, the right of deposit in New Orleans, and settlement of the northern border of the Floridas in the Pinckney Treaty in order to avoid potential hostilities with the United States. In the Treaty of Basel (July 22, 1795) Spain becomes an ally of France, and cedes her remaining two-thirds of the Island of Hispaniola (Santo Domingo) to France.

1797–1800:

The United States and France enter a period of “quasi war” over American neutrality rights.

1799:

On November 9–10, Napoleon Bonaparte seizes power in France.

1800:

Napoleon’s military victories in Italy against Austria (June) result in the redrawing of the political map; Spain is willing to trade - in return for her dynastic interests in Italy (now occupied by France), she will retrocede her colony of Louisiana to France. The result is the secret Treaty of San Ildefonso (October 1, 1800).

1801:

President Thomas Jefferson names Robert Livingston as United States Minister to France.

1802: April 18:

Jefferson writes to Livingston in Paris expressing his concern that “the day that France takes possession of New Orleans.… From that moment, we must marry ourselves to the British fleet and nation.”

1802: October 15:

Spanish King Charles IV retrocedes Louisiana to France, per the Treaty of San Ildefonso. Spanish Intendant Juan Ventura Morales in New Orleans closes the Mississippi River to Americans on October 16, and suspends their right of deposit in New Orleans in violation of Article XXII of the Pinckney Treaty. This action produces an outcry in the United States, and even talk of secession or hostilities from frontiersmen in Kentucky, Tennessee, and Ohio. Following peace with Britain in March, 1802, France plans for its Louisiana Expedition with funds, troops, and colonial administration. But the failure of French forces to pacify and suppress the slave revolt in Saint-Domingue (Haiti) results in reconsideration of the West Indies enterprise that included Louisiana.

1803:

In January, Jefferson nominates James Monroe to join Robert Livingston in Paris with instructions to seek a solution from France on behalf of American interests, including purchase of New Orleans and lands to the east. French Prefect Laussat departs France as head of the advance party to Louisiana, in order to prepare for the arrival of the Louisiana Expedition’s military forces.

1803:

March–May. Britain mobilizes and prepares for war with France because of the latter’s noncompliance with the terms of the Peace of Amiens signed in 1802.

1803:

In March, Napoleon cancels the Louisiana Expedition. On April 10, he decides to sell Louisiana, and the next day, he instructs Foreign Minister Charles Maurice de Talleyrand-Perigord, and Minister of the Public Treasury Francois Barbe-Marbois, to inform Livingston and Monroe that he is willing to sell all of Louisiana.

1803: March 26:

French Prefect Laussat, his family, and staff arrive in New Orleans to prepare for the anticipated arrival of the French Expedition.

1803: April 30:

The United States and France agree on a Louisiana Purchase price total of $15,000,000, which includes two conventions to the treaty that settled monetary disputes between US citizens and France stemming from the recent “quasi-war.” The documents are formally signed on May 2, 1803.

1803: July 4:

The Louisiana Purchase is officially announced in the United States, and President Jefferson calls for a special session of Congress to convene on October 17, 1803.

1803: August 18:

Official dispatches from France inform Prefect Laussat in New Orleans of the Louisiana Purchase, and provide instructions on how he is to proceed.

1803: October 20:

The Senate ratifies and the President signs the Treaty and two Conventions with France of April 30. On October 28 and 29, the House of Representatives votes the appropriations with which to carry the Treaty and Conventions into effect. Legislation completed, with amendments, and signed by President Jefferson on November 10, 1803.

1803: November 30:

French Prefect Laussat officially accepts Louisiana from Spain in New Orleans’ ceremonies.

1803: December 20:

American Commissioners William C.C. Claiborne and General James Wilkinson officially receive Louisiana on behalf of the United States from French Prefect Laussat in New Orleans.

1804: January 1:

Haiti declares its independence from France.

1804: January 16:

President Jefferson sends a message to Congress regarding the formal transfer of the Louisiana Territory to the United States from France, which includes a letter from William C.C. Claiborne and General James Wilkinson to Jefferson announcing the official transfer.

1804: March 26:

After lengthy debate in the House and Senate, the final law is signed by President Jefferson, “An act erecting Louisiana into two Territories [Territory of Orleans and the District of Louisiana] and providing for the Temporary Government thereof.” The Louisiana Purchase is now complete.