The Worst Peanuts Special Ever

Okay, maybe not ever. I'm not counting aberrations like and It's Flashbeagle, Charlie Brown, or You're Not Elected, Charlie Brown, or Try My Flugelhorn, Charlie Brown (and of those three, I only made one of them up). I'm talking about the big ones, the ones that we watched as kids prefaced with that giant CBS eye acid-trailing up at us "in Color!" You know, the classics. The Big Three: A Charlie Brown Christmas (1965); It's the Great Pumpkin, Charlie Brown (1966); and A Charlie Brown Thanksgiving (1973).

Why are these the Big Three?