1.2Cities, farms, and trade

Native North Americans built sophisticated societies. Around Cahokia, near present-day St. Louis, a Mississippian city of perhaps 10,000 to 20,000 people flourished around 1100 CE, centered on enormous earthen mounds. In the Southwest, Ancestral Puebloan peoples raised stone and adobe complexes at Chaco Canyon and Mesa Verde, linked by roads and aligned to the sky.

Agriculture reshaped the continent. The "three sisters"—maize, beans, and squash—spread north from Mexico and supported growing populations. Trade networks moved copper from the Great Lakes, shells from the Gulf, and obsidian across immense distances. These were connected worlds, with their own centers, peripheries, and long histories of rise and decline.