The 9th millennium BC in North American history provides a time line of events occurring within the present political boundaries of United States (including territories) from 9000 BC through 8001 BC in the Gregorian calendar. Although this time line segment may include some European or other world events that profoundly influenced later American life, it focuses on developments within Native American (and Polynesian) communities. Because the indigenous peoples of these regions lacked a written language, we must glean events from the admittedly very incomplete archaeological record and place them in time through radiocarbon dating techniques.
Because of the inaccuracies inherent in radiocarbon dating and in interpreting other elements of the archaeological record, most dates in this time line represent approximations that may vary a century or more from source to source. The assumptions implicit in archaeological dating methods also may yield a general bias in the dating in this time line.
- 9000 BC: Archaeological materials found on Channel Islands off the California coast and in coastal Peru.
- 9000 BC: Human settlers arrive in the Great Basin with its cool, wet prevailing climate.
- 9000 - 8900 BC: The Folsom culture in New Mexico leaves Bison bones and stone spear points.
- 8700 BC: Human settlement reaches the Northwestern Plateau region.
- 8500 BC: First Americans arrive at Tierra del Fuego, the Antarctic tip of South America.
- 8001 BC: The last glacial ends, causing sea levels to rise and flood the Beringia land bridge, closing the primary migration route from Siberia.
- 8001 BC: Sufficient rain falls on the American Southwest to support many large mammal species--mammoth, mastodon, and a bison species-—that soon go extinct.
- 8001 BC: Native Americans leave documented traces of their presence in every habitable corner of the New World, including the American Northeast, the Pacific Northwest, and a cave on Prince of Wales Island in the Alexander archipelago of southeast Alaska, possibly following these game animals.
- 8001 BC: Hunters in southwest Europe and the American Southwest both use the atlatl.