The Peopling of the Americas

During the last Ice Age, so much water was locked in glaciers that sea levels fell dramatically, exposing a broad land mass — Beringia — between Siberia and Alaska. The National Park Service’s Bering Land Bridge National Preserve protects a remnant of this landscape, across which people followed herds of large animals, many now extinct, into North America.

People moved for the same reasons as later migrants: to find food and survive. Over generations, small groups of hunters and gatherers spread into a continent of enormous ecological variety, adapting to tundra, forests, plains, deserts, and coasts.

For decades, the leading model held that people entered the interior around 13,000 years ago, once an ice-free corridor opened between the great glaciers, and that a distinctive stone-tool tradition called Clovis represented the first Americans. Discoveries at many sites have challenged that view, and the most dramatic evidence comes from White Sands National Park in New Mexico. There, at the edge of an ancient lake, researchers found fossilized human footprints — many apparently made by children and teenagers — in layers of sediment dated to about 23,000–21,000 years ago. The National Park Service notes that humans had previously been thought to arrive closer to 13,500–16,000 years ago.

Those dates mean people were in North America at the height of the last glacial period, when the interior route would have been blocked by ice. That has strengthened the case that some early migrants traveled along the Pacific coast, perhaps by boat, though the exact routes and timing are still debated.

Over thousands of years, the descendants of these first peoples populated both continents. They developed hundreds of languages and distinct cultures, domesticated plants such as maize, squash, and beans, and built societies ranging from small bands to cities.

By the time Europeans arrived in 1492, the Americas had been home to human societies for tens of thousands of years. Recognizing that depth of time corrects the old notion of the continent as an empty “New World.” Many Native nations, whose oral traditions describe their origins in their own homelands, view migration theories as only one way of understanding their past.