The Walter Mails set is actually a West Coast set. It was printed in California, and says so on the box they originally came in. The set contains both major and minor leaguers. Most of the major leaguers in the set however have ties either directly to the PCL or played in the Western US before going to the major leagues (a la Walter Johnson). Mails himself has a card indicating that he currently plays in the PCL but used to play for Cleveland. There are people playing for other minor leagues other than the PCL but I believe they were all former PCL guys. Here are some picture examples.Instruction card indicating cards produced in Santa Monica, CAMails himself:Another example of a PCL guy:Guy playing for Kansas City:Anyways, hope this helps.-Rhett