Being a native and lifelong Texan, I never quite understood it when, as a kid, I would be reading some Marvel comic book (was never much of a DC man, frankly) and one of my favorite characters would say "Natch." Usually it was Ben Grimm, who was full of slangy, yankee goodness. He was always saying some crazy shizznit.
Anyhow, it's only been recently that I caught on to it as a diminutive form of "naturally." Sorta interesting. Maybe.
Do people really say that up north, though?
Bully for them.