Christopher Columbus Day centers on the way Columbus and those who followed him treated Native Americans. 1492 marked the beginning of the end for the native people of North America. Most did not die from the diseases Europeans brought with them to the New World were killed outright, forced into slavery, or kicked out from their homes. The Europeans made in the New World were at the expense of the native population.
Recent evidence has also shown that Columbus was not even the first European to reach North America. That honor goes to a Viking Leif Erikson who visited what we know call Newfoundland almost 500 years before Columbus reached Hispaniola. It's a day of mourning for many native americans, therefore it shouldn't be respected as a holiday