Yellow is no parking here in Florida also. I seem to recall somewhere (Texas?) that used red to denote fire lanes in parking lots. I've been wrong in this thread, but I think any place you see a yellow curb in NJ is no parking. Usually they do go along with signs - no one's really trying to trap people into getting tickets. The curb color helps to define the extent of the rule when signs are ambiguous or not able to be posted at the start of the rule.
Up in Indiana, or at least at Purdue, loading zones were yellow and white striped curbs.
Now in which states do yellow (or red, green, purble, glow-in-the-dark, etc.) curbs have actual legal status? I've never really seen them without parking restriction signs or in situations where parking is otherwise illegal (hydrants, driveways, near corners). I'd be interested to know if the yellow paint in a location that would otherwise be unrestricted actually matters.
We normally have signs in Virginia, too, and normally they're posted every so often along the yellow curb ("No Parking or Standing/Fire Lane," sometimes with an arrow and sometimes without). The sign I posted in the other thread is something newer that I've only seen in a few places, namely the entrance to certain neighborhoods within the larger planned community where I live. But not all neighborhoods have those—on my street, for example, we have the more conventional signs posted every so often. I can certainly see why in a suburban residential area they might prefer to have a single sign at the entrance to a neighborhood, or at the beginning of a street, rather than multiple signs up and down the side. The added signs aren't the most eye-pleasing thing out there and it's more expensive to post additional signs. (Before anyone says it, yes, I realize that in cities there are signs all over, but I think it's fair to suggest that this is one of many differences between city and suburb.)
But I suppose this whole discussion does underscore the benefit of using some sorts of signs. If curb color meanings do differ around the country, then it's best not to assume people know what they mean.
BTW, here is the picture I posted in the other thread that prompted this whole discussion, just in case someone reading this thread didn't see it. The original context was that I was objecting to the misspelling of "Fire Lanes" as a single word when it's properly two words. ("Or" is spelled properly on the sign. I just took the photo at a dumb angle as I was driving past.)