State abbreviations in URLs

[Rob]

For 25 years, the AW river pages have used the standard two-character state abbreviations in the URLs. Why have these now changed to three characters? (It can't be to eliminate confusion with non-USA listings, since all USA listings have "USA-xxx" (where xxx is the state), whereas Canada listings have "CAN-xxx" for the provinces.)

Furthermore ... why do they not all conform (where possible) to more standard/historical three character abbrevations?
(Alabama historically was Ala, we now use ALB? Iowa was IOA, we now use IOW? Maryland was MAR, we now use MRY? West Virginia was WVA, we now use WVR? Wyoming was WYO, we now use WYM?)