you may be able to get an older Chip Rack (the guide for Nevada chips), which would give you more information on dates, numbers made, etc (up to the date of the copy you buy). I believe a new copy is around $50 (don't quote me, I don't actively collect Nevada chips, so I don't have one myself). For Mississippi, I have no idea. You may have to find the people who collect Mississippi and ask them.

Michael Siskin