Many people think that Cinco de Mayo should be a National Holiday even though it is a Mexican holiday to commemorate the Mexican Army's victory over the forces of the French in 1862.
That means nothing to me. I'm neither Mexican, and if I were of French descent I doubt it's an occasion I'd like to celebrate.
Many point out that we celebrate St. Patrick's Day which is Irish. First of all, St. Paddy's Day is NOT an official holiday. If it were, we would get the day off with pay. Secondly, it is basically religious. St. Patrick was the first Bishop Of Ireland. Ireland is predominently Catholic and so is Mexico. They do have that in common.
However Cinco de Mayo is non-religious and has meaning only to Mexicans - and it has nothing to do with Mestizos from countries other than Mexico. Unlike St. Paddy's Day, Cinco de Mayo has meaning for Mexicans only.