Well, politicians (even dead ones) are obviously out, Halloween the whole pagan thing, Christmas, don't even go there,  July 4th encourages making IEDs, Columbus imperialist, Easter S&M as per Mel G., Labor Day, socialist, Valentine's sexualizing the poor kiddies - IIRC, we gave cards to each other without regard to gender, a potential minefield.  Someone will probably realize that the groundhog, fearing its own shadow is a sign of a weak and timid America and lobby to have it replaced with the wolverine. 

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken