When flying, are customers still required to stop drinking alcohol?

Several years ago, wife and i flew to California. once we were in the air, drinks were served(alcohol). upon flying over one or two states, we were advised to stop drinking alcohol. all sales aboard stopped. was this becuase we were flying over a “dry” state? this may be an off-the-wall question, but no one gave us the answer onboard back then. so, what was with that?