Columbus Day

Today is Columbus Day in the US. This holiday always confuses me. It's considered an Italian pride day, but didn't Italy reject Columbus' theories? Didn't he have to change citizenship to Spain so the throne would finance his expedition to the New World? Really, shouldn't this be a holiday celebrating those who had the ability to see things in some other way that no one else could? Shouldn't we really be celebrating Spain for their contribution, without which, who knows when the New World would've been discovered?