I wouldn't carry on USPS property, but will in most posted local places (private businesses) because they won't know anyway. The exceptions there being public venues that are put off limits by the state.
A man can never have too much red wine, too many books, or too much ammunition
-Rudyard Kipling
I can't remember which State it is but if a business or venue declares itself as a gun free zone, they are obligated to provide you with a secure locker where you can safely stash your firearm.
95% of the time we stay OUT of gun zones i.e.. shooting galleries, but sometimes life forces us into those nasty places
If a private business property is posted in Texas, it's not a crime to carry concealed on it. It is however, if the carrier is "discovered" and asked to leave, but fails to comply. In that case it is a criminal trespass misdemeanor.
No private business or venue is required to provide a locker.
In some cases I will not enter a posted business, particularly if it is known that they donate to anti-2nd Amendment organizations.
When open carry passed & went into effect in Texas a couple of years ago, a lot of businesses were approached by the "Million Mom Marcher" types who persuaded them to post both their "no open carry" and "no concealed carry" signs at their entrances. Many of those businesses put both signs up, as they didn't understand the new law's requirements. They thought if they wanted to disallow open carry, they had to post both signs.
Of course LTC folks and the Texas State Rifle Association did a lot of footwork educating the businesses that they didn't have to put up both signs - and were going to lose some long time customers. So many of them took down the "no concealed carry" type signs, but did leave up the "no open carry" signs. A few still have both. They don't get my money.
A man can never have too much red wine, too many books, or too much ammunition
-Rudyard Kipling
Interesting. Signs that distinguish. Around here it's simply No Firearms or a variation thereof. As I noted before, they don't carry the force of law and I patronize several that do post because the signs are a corporate dictate that don't reflect the view of the individual shop owner.
NRA Benefactor