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The Declaration of Independence
By issuing the Declaration of Independence, adopted by the Continental Congress on July 4, 1776, the 13 American colonies severed their political connections to Great Britain. The Declaration summarized the colonists' motivations for seeking independence. [Office of the Historian] -
The adoption of the Constitution
The Constitution became the official framework of the government of the United States of America when New Hampshire became the ninth of 13 states to ratify it. [The National Constitution Center] -
The Louisiana Purchase
In this transaction with France, signed on April 30, 1803, the United States purchased 828,000 square miles of land west of the Mississippi River for $15 million. For roughly 4 cents an acre, the United States doubled its size, expanding the nation westward. [National Archives] -
The war of 1812
conflict fought between the United States and Great Britain over British violations of U.S. maritime rights. It ended with the exchange of ratifications of the Treaty of Ghent. [Britannica] -
Monroe Doctrine
The Monroe Doctrine was a foreign policy that outlined the United States' stance on the new political order in the Americas and the role of Europe in the Western Hemisphere. -
Mexican-American War
The immediate cause of the Mexican-American War was a disputed boundary between the United States and Texas on the Nueces Strip. [National Park Service] -
Treaty of Guadalupe Hidalgo
By its terms, Mexico ceded 55 percent of its territory, including the present-day states California, Nevada, Utah, New Mexico, most of Arizona and Colorado, and parts of Oklahoma, Kansas, and Wyoming. [National Archives] -
The Compromise of 1850
The bills provided for slavery to be decided by popular sovereignty in the admission of new states, prohibited the slave trade in the District of Columbia, settled a Texas boundary dispute, and established a stricter fugitive slave act. [National Achieves] -
Dred Scott decision
Eight of the nine justices wrote separate opinions. Seven justices, primarily pro-Southern, followed individual lines of reasoning that led to a shared opinion that, by law, Dred Scott was still a slave. [Missouri Secretary of state] -
Abraham Lincoln elected President
Lincoln took office following the 1860 presidential election, in which he won a plurality of the popular vote in a four-candidate field. Almost all of Lincoln's votes came from the Northern United States, as the Republicans held little appeal to voters in the Southern United States. [The White House]