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The Louisiana Purchase
The Louisiana Purchase was signed April 30, 1803. It reached Washington, D.C. on July 4 and was finally ratified by the Senate on October 20. The massive land-deal bought roughly 828,000 square miles of land. It was made for only $15 million, meaning each acre only cost about three cents. It doubled the size of the United States and began its plan for westward expansion. -
Adams–Onís Treaty
The Adams–Onís Treaty ceded Florida to the U.S. and included West Florida. It defined a boundary between the U.S. and New Spain. It was signed on Februaury 22, 1819, but it was not until October, two years later, that it was ratified and proclaimed. Instead of paying for Florida, the U.S. agreed to pay up to $5 million in legal claims of American citizens against Spain. It was officially called the Transcontinental Treaty, and was known by other names. -
Texas Annexation
In 1836, Texas declared its independence from Mexico, and many people favored its annexation by the United States. However, Mexico threatened to go to war if it happened, so the idea was put down. Later in 1844, President John Tyler tried again through a treaty, but it lacked the number of votes neccessary for ratification. He tried again with a joint resolution of both houses and it was passed March 1, 1845. On December 29, it was signed by President Polk and Texas became the 28th state. -
Oregon Treaty
The boundary between the United States and British North America along the 49th parallel was disputed and shared for many years in the early 1800s. Some Americans wanted more land up to parallel 54°40′ north. U.S. Secretary of State James Buchanan negotiated a treaty to separate both nations at the 49th parallel, which was signed on June 15. The size of the area is approximately 286,000 square miles. -
Mexican Cession
The Mexican Cession covered nearly 530,000 square miles. The United States paid $15 million for the land, but after defeating Mexico's army, taking the capital, and more or less forcing them into a treaty. They also paid $3.25 million for claims of American citizens against Mexico. All of this was done through the Treaty of Guadalupe Hidalgo, which was ratified by the Senate with a vote of 38–14. -
Gadsden Purchase
The Gadsden Purchase was made for $10 million by James Gadsden and ratified by the U.S. Senate on April 25, 1854. It confirmed the border between the U.S. and Mexico and allowed a southern route for the transcontinental railroad. It covered some 29,640 square miles.
