What 1803 deal transferred a vast territory from France to the United States?

The Louisiana Purchase was the 1803 deal that transferred a vast territory from France to the United States.

The United States agreed to pay France $15 million for approximately 828,000 square miles of territory west of the Mississippi River. The land stretched from the Mississippi basin toward the Rocky Mountains, although its exact boundaries were not immediately clear.

President Thomas Jefferson authorized the purchase after negotiations led by James Monroe and Robert R. Livingston. France’s Napoleon Bonaparte, facing war and financial pressures in Europe, decided to sell the territory rather than continue trying to maintain a North American empire.

The purchase nearly doubled the size of the United States and strengthened control of the Mississippi River and the port of New Orleans. It also created major constitutional and political questions, including how the federal government could acquire territory and how slavery would expand westward. The Lewis and Clark expedition later surveyed part of the new territory.