Hi Torrey, Not sure if you realize it, but those plaques were made after the casino closed as add on to poker sets made of the original chips.
Here is a link to a couple of discussions about them:

https://www.pokerchipforum.com/threads/questions-about-empress-plaques.45081/

https://www.pokerchipforum.com/threads/local-empress-plaque-score.87160/