Final answer:
Thomas Jefferson ordered the exploration of the new territory through the Lewis and Clark Expedition after the Louisiana Purchase, which was aimed at mapping the new lands and identifying routes for commerce and expansion.
Step-by-step explanation:
Following the Louisiana Purchase, Thomas Jefferson ordered the exploration of the new territory. In 1803, once the purchase was signed, Jefferson appointed Meriwether Lewis to head an expedition, known as the Lewis and Clark Expedition, to explore and map the vast new lands. This was an essential step for the United States, enabling the country to ascertain what they had acquired, ease future settlement, and assert control over the region. Additionally, this exploration was aimed at finding a potential water route to the Pacific and assessing commercial exploitation opportunities. While Jefferson did contemplate the removal of Native American tribes and even proposed their relocation to lands west of the Mississippi River, the widespread implementation of these policies primarily occurred during the presidency of Andrew Jackson.