AP U.S. History · Lesson 2

The Columbian Exchange

Know Know it

The Columbian Exchange was the movement of plants, animals, diseases and people between the Eastern and Western Hemispheres after 1492. It changed diets, landscapes and populations on both sides of the Atlantic.

From the Americas to Europe, Africa and Asia went maize, potatoes, tomatoes, cacao, cassava and tobacco. Over the next centuries, these crops spread to farms across Europe, Africa and Asia.

From the Eastern Hemisphere to the Americas came horses, cattle, pigs, sheep, wheat and sugarcane, and diseases such as smallpox, measles and influenza. Native peoples had no immunity to these diseases. Epidemics killed a very large share of the Native population in many regions within a few generations; estimates of the totals vary widely, but historians agree the losses were catastrophic.

Disease shaped conquest. Smallpox struck the Aztec capital of Tenochtitlan in 1520, weakening its defenders before Hernán Cortés and his Native allies took the city in 1521.

Animals reshaped Native life too. Horses that escaped or were traded from Spanish settlements spread north, and by the 1700s many Plains peoples had become mounted bison hunters.

Trap Not only guns and steel

It is tempting to explain Spanish victories by weapons alone. Epidemics often struck before or during a conquest, and thousands of Native allies, such as the Tlaxcalans, fought beside the small Spanish forces. A strong answer names disease or alliances, not just technology.

Worked example Easy

Which of these traveled from the Americas to Europe after 1492?

  1. Sugarcane
  2. Horses
  3. PotatoesAnswer
  4. Smallpox

How to solve it

  1. Sort each item by the direction it crossed the Atlantic after 1492.
  2. Potatoes went from South America to Europe; the other three were carried from the Eastern Hemisphere to the Americas.

Why each choice is right or wrong

  • A. Incorrect. Sugarcane came from the Eastern Hemisphere and was carried west to the Caribbean and Brazil.
  • B. Incorrect. Horses had died out in the Americas long before and were brought back by the Spanish, so they traveled west.
  • C. Correct. Potatoes were first grown in the Andes of South America and became a staple in parts of Europe.
  • D. Incorrect. Smallpox came from the Eastern Hemisphere and devastated Native peoples in the Americas.

Explain Explain it

Task verbs: explain, describe

To explain an effect of the exchange, follow one item across the ocean in three steps: what it was, who received it, and what changed for them. A single, well-traced item beats a list of five.

Worked example Medium

How did the arrival of horses change life for many Plains peoples by the 1700s?

  1. They gave up hunting and became full-time farmers
  2. They could hunt bison over far larger areasAnswer
  3. They stopped trading with neighboring peoples
  4. They moved east into the forests of the Atlantic coast

How to solve it

  1. Ask what a horse does for a hunter: speed and range.
  2. More range meant following bison herds over larger areas.
  3. Eliminate choices that point away from the Plains or away from hunting.

Why each choice is right or wrong

  • A. Incorrect. Horses pulled many peoples toward full-time hunting on the Plains, not away from hunting into farming.
  • B. Correct. Mounted hunters could follow bison herds much farther and kill more of them, and horses also changed travel, trade and warfare.
  • C. Incorrect. Horses made travel easier, so trade with neighboring peoples generally grew rather than stopped.
  • D. Incorrect. Peoples who took up horses moved onto the open grasslands, not east into the Atlantic coast forests.

Explain Your turn

Name one crop that crossed from the Americas to Europe, Africa or Asia after 1492. Then explain one way it changed life where it arrived.

Write it, then compare. Nothing you type here is saved or graded.

Compare with a model answer

A full answer does this

  • Names a crop that came from the Americas
  • Explains one accurate change that crop caused where it arrived

Model answer

Potatoes, first grown in the Andes, crossed to Europe after 1492. They grew well in cool, wet places where grain crops often failed and produced a lot of food per acre, so in places like Ireland and parts of northern Europe they became a staple that fed more people and helped populations grow.

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