Don, I think they are all letters "C." I got the info. from the shipping archive chip sample records of the U S Playing Card Co. The three chips on the top are from the St. Louis, Mo., "Columbian Club." The chips were shipped from 1919 to 1930. I'd sell these chips for $10.00 each till my initial supply runs out (not so many).

The one blue chip on the bottom is from the Chicago Club, Chicago, Ill. (1919 to 1924). No dupes to offer here. Similar "C." I am often wrong, but I'd say they are all C's.

Robert