If you live in New York or California, you are probably not used to the idea that most states have laws that permit the carrying of concealed weapons in many public places. In most of those permissive states, private entities can regulate whether you can pack your gun on their property. The result is frequent signage that states the rules.
Here are a couple of samples:
That one was here, in Las Vegas.
Somehow, this one is even more disconcerting:
I often wonder how foreign visitors see us.