Which U.S. territory was acquired through the Louisiana Purchase?

The correct answer identifies the vast territory that was acquired through the Louisiana Purchase as being west of the Mississippi River. In 1803, the United States, under President Thomas Jefferson, purchased this large expanse of land from France, effectively doubling the size of the nation at the time. The purchase included land that would eventually become all or part of 15 states, significantly broadening U.S. territory and facilitating westward expansion.

The context of the Louisiana Purchase is crucial; it was not just a small transaction but a significant geopolitical event that opened up an enormous area for settlement and exploration. This area was largely uncharted and included valuable resources, encouraging migration and development.

The other options refer to territories or areas that did not form part of the Louisiana Purchase, such as the area east of the Mississippi, which was already settled, as well as Texas and Florida, which were acquired later through different means.