More details below the infographic if you want to dig deeper.
Here are more details for each of these legendary real estate deals:
1. Alaska Purchase (USA from Russia, 1867)
Negotiated by U.S. Secretary of State William H. Seward and Russian minister Edouard de Stoeckl.
The treaty was signed March 30, 1867, ratified by the U.S. Senate on May 15, and American sovereignty was officially established on October 18, 1867.
The U.S. paid $7.2 million for nearly 600,000 square miles (about 2 cents per acre).
At the time, the purchase was called "Seward's Folly" and "Seward's Icebox" by critics who thought Alaska was worthless. Gold discovered in 1896 and oil later on proved them very wrong.
Alaska was sparsely populated until the gold rush and became a U.S. state in 1959.
2. Louisiana Purchase (USA from France, 1803)
Negotiated by American envoys Robert Livingston and James Monroe in Paris; signed on April 30, 1803.
The U.S. bought 828,000 square miles west of the Mississippi River for $15 million (just under 4 cents an acre).
France, under Napoleon Bonaparte, sold the land to fund wars and prevent it from falling into British hands.
Nearly doubled the size of the U.S., stretching from the Mississippi River to the Rocky Mountains, and included parts or all of 15 present states.
The U.S. originally sought only to buy New Orleans; France unexpectedly included the huge stretch known as Louisiana Territory.
The purchase became official on July 4, 1803, when word reached the U.S. government.
3. Florida Purchase (USA from Spain, 1819)
Also known as the Adams–Onís Treaty or Transcontinental Treaty.
Signed on February 22, 1819, but ratified and effective by 1821.
Spain transferred Florida to the United States, settling boundary disputes and relinquishing claims to the Oregon Country.
The U.S. agreed to pay "up to $5 million" in claims by American citizens against Spain, not a direct payment to Spain, for vast tracts of land.
The treaty helped secure the southern border, end piracy and border raids, and shape the map of the American southeast and west.
Spain ceded Florida mainly because it was unable to govern or defend it and was losing grip on its colonies in the Americas.
4. US Virgin Islands (USA from Denmark, 1917)
The U.S. bought the Danish West Indies (now US Virgin Islands: St. Thomas, St. John, St. Croix) from Denmark for $25 million in gold.
Deal was struck because of the islands' strategic location near the Panama Canal and World War I concerns (fear of German U-boat bases).
Danish residents and islanders voted in favor of the sale in a referendum in Denmark.
The U.S. formally took possession on March 31, 1917, renaming them the US Virgin Islands.
Besides their military importance, the islands blossomed into a tourism and vacation destination.