We generally find two sides to a coin. Well worth reading:
http://en.wikipedia.org/wiki/Columbus_Day
Opposition to Columbus Day dates to at least the 19th century where activists had sought to eradicate Columbus Day celebrations because of its association with immigrants and the Knights of Columbus. They were afraid it was being used to expand Catholic influence. By far the more common opposition today, decrying Columbus's and Europeans' actions against the indigenous populations of the Americas, did not gain much traction until the latter half of the 20th century. This opposition has been spearheaded by indigenous groups, though it has spread into the mainstream.
There are two main strands of this critique, which are interrelated. The first refers primarily to the indigenous population collapse and cruel treatment towards indigenous peoples during the European colonization of the American continents which followed Columbus's discovery.
A second strain of the criticism of Columbus Day focuses on the character of Columbus himself. In time for the observation of Columbus Day in 2004, the final volume of a compendium of Columbus-era documents was published by the University of California, Los Angeles's Medieval and Renaissance Center. Geoffrey Symcox, the general editor of the project, asserted: "While giving the brilliant mariner his due, the collection portrays Columbus as an unrelenting social climber and self-promoter who stopped at nothing— not even exploitation, slavery, or twisting Biblical scripture— to advance his ambitions…
