Final answer:
The claim that the Louisiana Purchase doubled the territory of the United States is true, as it added approximately 828,000 square miles to the country.
Step-by-step explanation:
The statement that the Louisiana Purchase doubled the territory of the United States is true. Before the Louisiana Purchase, the United States was approximately 827,000 square miles in size. With the acquisition of the Louisiana territory from France in 1803 for $15 million, the country gained an additional 828,000 square miles, nearly doubling its size. This expansion provided the young nation with vast new resources, opened up more land for settlement, and played a significant role in its westward expansion.