I recently read somewhere that most credit card processing centers on the East coast service card holders in the West and vis versa. It was suggested that this was because less affluent customers may have to wait until the last moment to send their payments for fear of creating overdrafts. This gives the CC companies an increased chance to tack on late fees if the payment doesn't make it on time. I also read from an ex-CC company employee that a small percentage of incoming mail was left unopened for a few day to increase the likelihood of adding late fees. I don't know if this has been documented and any companies fined for this behaviour but it wouldn't surprise me if it were true.
John Thornton