On Sat, 16 Jul 1994 12:40:32 EST,
Chris  <[log in to unmask]> wrote:
 
>   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.
 
CHRIS,   two-letter abbreviations became "official" with the advent of the
USPS ZIP-Code (or at least thats what my philatelic phriends say). Not sure
of the date, though the mid 60s is my recollection. It was (is?) all
volontary anyway so its only a partial indicator.           Best,   JIM