Some collectors believe that Obsolete means that you can no longer cash in the chip at the casino. In Atlantic City, if a casino has changed hands and the new owners issue new chips, they still have to cash in the chips from the former casino. So this definition of obsolete is faulty, at least in Atlantic City.

Another way of looking at it, and I believe that this is what most collectors believe, is that Obsolete means that chip is no longer in use at the casino. NO LONGER IN USE means that the casino is closed or that the chip has been replaced by a new rack. I have seen casinos that allow older racks to be used along with newer racks, especially if the colors and edge markings (inserts) are the same. But, you cannot reliably get the older rack chips, so they are obsolete.