Final answer:
The Louisiana Purchase included two main physical features: the Mississippi River and the Rocky Mountains. The Mississippi was crucial for trade and internal navigation, while the Rockies encouraged further exploration and westward expansion. This territory became central to the United States' growth, both in size and in economic power.
Step-by-step explanation:
The question appears to contain a typo regarding physical features "between" the Louisiana Purchase, which does not conceptually apply to a single territorial entity. Instead, we will discuss the prominent physical features within the purchased territory as well the importance of this boundary to the United States' expansion.
The Louisiana Purchase was a significant land acquisition for the United States in 1803. Two major physical features within the Louisiana Purchase are the Mississippi River and the Rocky Mountains. The Mississippi River was of vital interest for transportation and trade, allowing for the movement of goods and access to the interior of North America. The Rocky Mountains served as a geographical marker that spurred the drive for further exploration and expansion during westward expansion, becoming the setting for the Lewis and Clark Expedition.
This transaction, negotiated by Thomas Jefferson's envoys Robert Livingston and James Monroe, doubled the size of the United States overnight. It provided a vast expanse of land for the Jeffersonian vision of an agrarian republic and was a move of strategic importance, securing control of the Mississippi River and New Orleans. The purchase also underpinned the westward expansion of the country, which eventually became a contentious issue because of the debate over slavery in new states and territories.