Actually they are posted on the entry ways of most public buildings. I know they are posted around here on all super markets, resurants etc if you are not supposed to carry a concealed firearm. You should look more closely at the stickers posted on the front entry ways if you are concealing. If you are caught with a concealed weapon in a buisness that has it posted you may have your ccw suspended.Pisses you off don't it. If everyone was able to carry, not just concealed, but on their hip there would be ALOT less criminal behavior. The morons that make these laws don't relize this or are to ignorant to see it. Libererals mostly but not entirely, sad to say.
I think Nightowl meant that what meets the requirements for posting in one state, may not be enforceable in another. In Texas, for instance, a business owner can post a sign with letters 5 feet tall that says, 'NO CONCEALED HANDGUNS! EVEN WITH A LICENSE!' and it would not legally prohibit license owners from entering. We, thankfully, have very specific posting requirements. I have no idea what is sufficient in, say, Missouri (Picture of a gun with a line through it? 3"X5" notecard that says 'No Weapons'?
I can carry into a liquor store in Texas, can I do that in Colorado? I don't know. What about banks, or police stations, or...? I know my own state laws regarding these, but not other states.
I'm not actually looking for answers to these questions, I'm just pointing out that the state concealed carry laws are all very different in respect to specific requirements.