The United States bought the Louisiana Territory from France in 1803. It was a huge area west of the Mississippi River that later became all or parts of many U.S. states.

What it included

  • Most of the land between the Mississippi River and the Rocky Mountains.
  • The purchase covered about 828,000 square miles.
  • It roughly doubled the size of the United States at the time.

Why it matters

  • It opened the door to westward expansion.
  • Later, land from the purchase became states such as Louisiana, Missouri, Arkansas, Iowa, and others.

TL;DR: The U.S. bought the Louisiana Territory in 1803.