Although it's a bit counter-intuitive, Columbia actually never explored North America, instead visiting the other locations on this list instead. This lead to great discoveries but lots of suffering for the local inhabitants. <span />
But, here is who did explore North America: Several theoretical contacts have been proposed, but the earliest physical evidence comes from the Norse or Vikings. Erik the Red founded a colony on Greenland in 985 CE. Erik's son Leif Eriksson is believed to have reached the Island of Newfoundland circa 1000, naming the discovery Vinland.
