Codes

["John B. Thomas, III" <johnbarney@mail.utexas.edu>]

     Although the Zone Improvement Plan (ZIP) introduction date may be
known, it was preceded by at least one decade by zones within major cities
in the U. S.  My grandmother's address in the 1950s ended, as I recall, Los
Angeles, 12, Calif.  I believe that these city zones began in New York, and
that more cities were gradually added.  These city zones may now be
incorporated into the relevant ZIP.  In England, such city zones began in
London in the 1850s, and a national system of postcoding was established
between 1966 (at Norwich) and 1972 (London).
     I don't think that any date can be given, other than locally, for
changes in the digits in telephone exchanges.  There are many places in the
world now that have telephone numbers with less than seven digits, and
sometimes the practice is at variance with the recorded information.  For
example, in a certain small town that I know in South Texas, ALL prefixes
are still 334 (formerly FEderal 4) in seven digit numbers, and until fairly
recently it was possible to complete a local call by dialling only the last
five digits.
     John B. Thomas, III