Final answer:
The Louisiana Purchase doubled the size of the United States.
Step-by-step explanation:
After spending $15 million on the Louisiana Purchase in 1803, the size of the United States doubled. The purchase included the vast western territory, stretching from the Mississippi River to the Rocky Mountains, and almost doubled the size of the country overnight. This acquisition greatly expanded the land available for settlement and paved the way for westward expansion and the development of the United States as a continental nation.
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