2.1The Columbian Exchange

Columbus's voyages opened a two-way transfer of people, plants, animals, and microbes now called the Columbian Exchange. From the Americas came maize, potatoes, tomatoes, and tobacco, which transformed diets worldwide. From Europe came horses, cattle, pigs, wheat, and sugar cane.

The deadliest travelers were invisible. Smallpox, measles, and influenza, to which Native peoples had no immunity, swept through communities with catastrophic force. In many regions populations fell by 70 to 90 percent within a century or two. This demographic collapse, more than any battle, cleared the way for European settlement and reshaped Native societies that survived.