A schematic picture of North America at the height of the last Ice Age.  This is a view derived mainly from the evidence of topographic maps, which suggest where the ice and snow may have lay.  It is not intended as a snapshop at any instant of time, nor are the details necessarily in accord with evidence from other sources.

The location of the ice is crucial to one aspect of human history: how did people migrate from Asia, reaching the interior of North America by about the time of the Last Glacial Maximum (LGM).  Careful consideration of the topography suggests that the route that has been favored by some historians, geographers, and antrhopologists, between the Rocky Mountains and the Laurentian Ice Cap, may have been impractical until long after the LGM.  Many anthropologists and paleontologist now favor a route along the coasts.  It is most likely that the human and animal migrations used several routes, both along the coast and inland.

Perhaps I may venture a suggestion here that humans reached the interior of North America by both inland routes and by coastal routes.

The topics considered here are

• Introduction: Where did the Ice Age Glaciers Lie?