Why do we have Columbus Day??

I have been learning a lot doing school with the boys. We are learning American history this year. I study it first so I'm not in the dark when I teach them. I've been reading about Christopher Columbus today. I am baffled as to why we have a national holiday celebrating this man??

He sailed to a new land, not knowing where in the world he was, made slaves out of the natives and sent some back to sell as slaves, and his crew that he left ransaked the villages. Since he didn't know where in the heck he was, he made his crew sign an oath to lie and say that they had made it to China, and if they said anything different their tongues would be cut out. He was a know-it-all, and when he died, he still swore he found China, even though "by this time others had accepted the fact that there was indeed a new continent, Columbus never budged from his fixed ideas of geography. He had been to China, he insisted, and if he'd had more time, he would have reached Japan." And he wasn't even the first to "discover" America. The viking Leif (Eric the Red's son) sailed to America long before Columbus. And he only "discovered" America from a European's standpoint.

Because of Columbus, "the whole world was changed forever. Europeans considered this New World their own to explore, to exploit, to settle, to do with as they pleased. And the native peoples of this New World gradually lost their land, their peace, their freedom, and all too often their lives." (Quotes from Around the world in a Hundred Years by Jean Fritz) Why are we celebrating a closed-minded, dishonest, slave-trading man who didn't even know that he had discovered America??

I think I'll write to the politicians.

PS From looking online for a short bit, I've learned that the Italian people here started celebrating Columbus Day because he was Italian, and then President Nixon decided to make it a national holiday.

PSS I'm finding out that other people in history who are "honored" were not so great. Thomas Jefferson, the writer of the Declaration of Independence, a president of our country, owned slaves and started the idea of kicking the native americans out of "our" country--the very man who wrote about freedom and owning land etc. being self-evident truths. There are so many events in our country's history that are not noble. I told the boys when we started history last week, that our country has made many mistakes, that it's not perfect, but even still, it's the "land of opportunity" where we have so many blessings that we should be grateful for.