In 1803, The U.S. doubled in size practically overnight when it purchased about 828,000 square miles of territory from France. President Thomas Jefferson had sent some envoys (including future president James Monroe) to Napoleon to see about buying the Port of New Orleans as a way of protecting it from Spanish blockades. Instead, France surprised everyone by offering a huge territory that stretched from the Gulf of Mexico to Canada. Apparently, Napoleon, who'd hoped the territory would supply goods to support his lucrative sugar business in Haiti, had found it too much of a hassle and expense to maintain the sprawling Louisiana territory.

Napoleon made the U.S. an offer it couldn't refuse: $15 million bucks for the whole shebang. That's less than 3 cents per acre, a steal even in today's money. The envoys, who'd been authorized to offer $10 million just for New Orleans and its neighborhood, jumped on the deal and relayed the news to Jefferson.

As soon as the purchase was a done deal, trouble started a-brewin'. Everyone knew there would eventually be states made out of all that territory, which raised the eternal question: would they be slave or free? There had always been a delicate balance in the new nation of slave and free states; would this gigantic purchase upset the balance?

Over the next fifty years, the Purchase would cause major conflict between north and south. Thirteen new states were eventually created from it, and there were battles over slavery in almost every one. Much of the legislation that regulated slavery in the states came from arguments over the territory gained in the Louisiana Purchase, the gift that kept on giving (source).

Psst: we've got a whole learning guide on this one, too.