why so many California hats??

[rondo]

Yes. Texas.

^ What David said.
Rondo

[Nottawayblue]

While not the state flag, I still seem to think NY wins with the countless variations of the Yankees cap seemingly adopted as the official state pride headwear. Can't even think of all the combinations (most pretty ghastly) I've seen.
Although, Hawaii ranks right up there. There are a LOT of locals wearing hats with state flags / stylized state flags / other state heritage icons. Offs, seems to not be strictly confined to California.