If you click on the image in the auction, Andy, a much larger version will open and you will see that the opening and closing dates of each casino appears on the chips. They are, however, great looking pieces with some history unto themselves and are collectible.

And by the way, glad to see you'll be attending Casinorama. It's a good first show to get to... plenty of action. While you're there, you'll be able to recognize Mr. Bedo pretty easily... he'll be the one wearing the blank expression and ripped Grateful Dead tee shirt.