Christopher Columbus deserves credit for literally putting America on the map in 1492, but he followed other explorers who did not stake a monarch’s claim to the lands they discovered. Some are celebrated in ancient texts in which it is difficult to separate history and mythology. Others arrived thousands of years earlier, when the Americas had yet to be inhabited by humans, and they left no paper trail. The main source of clues about who first reached our shores lies in the earth itself. “Archaeology lets us look into deep time—before historical records—and allows us to extend history,” says journalist Heather Pringle. In our cover story, “Who Really Discovered America?,” Pringle casts a critical eye on the claims of a host of intrepid trailblazers who may have journeyed here long before Columbus sailed the ocean blue.