In attempting to date certain commercially produced artifacts, it would be very helpful to know when the two-capital-letter state abbreviations came into use -- Ind. became IN, etc. Also, does anyone have a handle on the Calif. -> Cal. and Penna. -> Penn. -> Pa. shifts in common usage? People in the post office here have no idea, and Polk's city directories still use "Mich." on their title page! TIA, Chris Bobbitt [log in to unmask] Curator of Collections Monroe Co. Historical Museum Bloomington, Ind. (sic)