President Thomas Jefferson sought to purchase the town of New Orleans and the surrounding territory, then simply known as the Louisiana Territory, from the French in order to secure trading routes for the United States. He wanted to prevent any disruption in American economics that would come from disrupted trade.
In 1800, under the leadership of Napoleon Bonaparte, France had successfully reclaimed a large swath of land from Spain in the Treaty of San Ildefonso. France had previously possessed the land but lost it to Spain during the tumultuous period prior to Napoleon. Once France regained control of the Louisiana Territory, it began implementing new laws and regulations in its largest cities, specifically New Orleans. New Orleans was one of the largest ports in the gulf, and it served as a major hub for importing and exporting goods.
The fledgling American nation relied heavily on New Orleans to both receive new goods as well as to sell its own goods to Europe. Jefferson feared that over time France would impose harsh taxes and other restrictions on American use of the port, but instead of declaring war with France to seize the land, he opted to purchase it instead. France ultimately agreed and altered the deal to include significantly more land.