President Thomas Jefferson authorized the Lewis and Clark expedition, also known as the Corps of Discovery, for several reasons. One of the main reasons was to explore and map the newly acquired western territory of the United States, which included the Louisiana Purchase. Jefferson wanted to learn more about the natural resources, plant and animal life, and indigenous peoples of this vast region. He also hoped to find a practical route for American settlers and traders to travel to the Pacific Ocean, as he believed this would open up new economic opportunities for the young nation. Additionally, Jefferson wanted to establish American sovereignty over the territory and to assert the country's presence in the region.