The primary significance of the Louisiana Purchase in 1803 was its considerable expansion of the United States territory by acquiring approximately 828,000 square miles from France. This acquisition doubled the size of the nation and opened vast tracts of land for westward exploration and settlement. It served as a critical step towards fulfilling the concept of Manifest Destiny, shaping the future economic and political landscape of the U.S. The purchase also paved the way for a variety of conflicts over land and resources with indigenous peoples and foreign powers, fundamentally altering the trajectory of American history.