The history of North America from its 1.8-billion-year-old Laurentian craton to the first people to reach it. It follows the 2.5-mile-thick Laurentide ice sheet that carved the Great Lakes, the Beringia land bridge and the 900-mile ice-free corridor that failed as a route, and the finds that rewrote the timeline — the 21,000 to 23,000-year-old footprints at White Sands and the 16,000-year-old points at Cooper's Ferry predating Clovis — to the April 25, 1507 Waldseemuller map that first printed the name America.