Which 1803 acquisition from France added a vast central region to the United States?

The 1803 acquisition from France that added a vast central region to the United States was the Louisiana Purchase.

The United States agreed to pay France $15 million for the territory, which stretched from the Mississippi River toward the Rocky Mountains and from the Gulf of Mexico northward. The treaty was signed in Paris on April 30, 1803, and the agreement was publicly announced in July.

President Thomas Jefferson had initially focused on securing New Orleans and navigation rights on the Mississippi River. Napoleon Bonaparte instead offered the entire Louisiana Territory, partly because France had abandoned plans for a major North American empire after resistance in Saint-Domingue and renewed conflict with Britain.

The purchase nominally covered about 828,000 square miles, though France did not exercise effective control over all of the land and many Indigenous nations lived there. The acquisition nearly doubled the geographic size of the United States and became a major source of later territorial expansion.