The major benefits of the Louisiana purchase were the vast expansion of the territory of the United States and the acquisition of an abundance of natural resources for a modest price. It removed France as a colonizing presence in the area and gave the United States the important port of New Orleans and the trading channel of the Mississippi River.
The Louisiana purchase encompassed about 828 million square miles of territory from the Mississippi River to the Rocky Mountains. Although much of it was unexplored, it enabled the rapidly growing population of the United States to expand westward. Shortly after the agreement for the Louisiana purchase was signed, Meriwether Lewis and William Clark set out to explore the new territory. Their discoveries of new flora, fauna, landscapes and natural resources enabled the U.S. government to grasp the value of what they had acquired. The Louisiana purchase also led to the eventual acquisition of the Oregon Territory, which allowed the United States to expand to the Pacific Ocean.
Although the acquisition of the Louisiana territory at the price of 3 cents an acre is considered one of the high points of Thomas Jefferson's presidency, at the time it was extremely controversial. Many politicians considered it illegal, because the U.S, Constitution made no provision for the acquisition of territory. Arguments erupted about the citizenship of the people already living in the area. However, Jefferson went ahead because he felt that the benefits outweighed any possible disadvantages.