Seeking a sea route to Asia, Christopher Columbus (sailing for Spain) landed in the Caribbean in 1492. This contact began the Columbian Exchange —a vast transfer of plants, animals, diseases, and people between the Eastern and Western Hemispheres. Europeans brought horses, wheat, and sugar; they took back maize, potatoes, and tobacco. Devastating diseases like smallpox wiped out up to 90% of some Native populations.

Written mainly by Thomas Jefferson , the Declaration listed grievances against King George III and asserted natural rights—“Life, Liberty, and the pursuit of Happiness.” It was adopted by the Second Continental Congress .

The United States was born from a fight for independence and the ideal that “all men are created equal.” Yet from the start, the nation was divided over slavery, Native American lands, and the power of government. The Revolution created the nation; the Constitution created a government; the Civil War tested whether that nation could survive; and Reconstruction attempted—but ultimately failed—to secure true freedom for all. By 1877, the U.S. remained a country still struggling to fulfill its founding promises.

President Thomas Jefferson purchased the Louisiana Territory (1803) from France for $15 million, doubling U.S. size. He sent Lewis and Clark to explore it to the Pacific.

In April 1775, British troops marched to Concord, Massachusetts, to seize colonial weapons. At Lexington and Concord , the “shot heard ‘round the world” started the war.

Britain and France (plus Native allies) fought over control of the Ohio River Valley. Britain won but was deeply in debt. To raise money, Parliament began taxing the colonists directly.

Reunite the nation and define freedom for 4 million newly freed African Americans.