When did Indiana change their abbreviation from IND?

Answer 1

The conventional abbreviation for Indiana is Ind. It has been for at least a century, and it still is. The postal code for Indiana is IN. On July 1, 1963, the U.S. Post Office inaugurated the five-digit ZIP codes system. At the same time, it published a list of two-letter state codes, intended to be used in addressing mail.

Because it's hard to remember two abbreviations for every state, a lot of people use the postal state codes instead of the conventional abbreviations. The postal codes don't contain periods. You would write "Milwaukee, WI" on an envelope, for example.

Other examples:

Connecticut: conventional abbreviation, Conn.; postal code, CT.

Iowa: has no conventional abbreviation because it's already short; postal code, IA.

New Mexico: conventional abbreviation, N.Mex.; postal code, NM.

Pennsylvania: conventional abbreviation, Pa.; postal code, PA.