Which group of people left evidence of exploration in the americas before columbus?

trumans defeat to eisenhower in the 1948 elections was due to trumans approach and handling of the cold war and the war in korea. trumans approach to communism during the cold war was the principle reason for his defeat. eisenhowers reputation and name as the supreme allied commander in europe during world war two and his campaign slogan that he ''would go to korea if elected'' won him the presidency.