Sure, but Dallas ain’t the east or west coasts, and even in the Midwest, it’s probably pretty spotty from one locale to the next on whether or not you’ll see them being worn. I think big straw/woven sun hats are probably more uniformly worn across the country than cowboy hats.
Now, if we were talking about baseball caps with a sports logo on it, then I’d say it’s as endemic to every corner of the country as oxygen is.