Columbus returned to Spain with the wealth he had promised the Queen for financing his journey and it was enough to acquire funding for more trips. Without the bounty of slaves he would have been a one trick poney. It is impossible to discover a place that already has inhabitants of millions of people so it is accurate to say that he arrived in America in 1492 behind many others that arrived before him. His greatest contribution was establishing the slave trade with deaths numbering in the multiple millions of the unwilling natives. It's difficult to refer to this as an accomplishment but that is who we were. That is the one defining act that provided the progress we so willingly enjoy today. The crop production of the 17th and 18th  century,the railroad and all the transportation arteries of the 19th century all on the backs of slaves. The question lingering today is, is that who we still are? The president should not have given any support to nazi and klan member demonstrations.