On Mon, 26 Jun 2006 Stephen Sprunk wrote:

In general, all punctuation and diacritical marks are dropped to make
signs and addresses as easy to read/write as possible. Therefore "St.
John's" becomes "St Johns" (notice the two changes).

Well, the first change is welcome because your original is wrong IMHO.
To quote the Concise Oxford Dictionary "Abbreviations are made chiefly
in two ways....(2)Some portion of the middle of the word is dropped out,
the first and last letter being retained...the writing of a full stop at
the end of these, though now usual, is to be deprecated....The method
adopted in the following list is to omit the otiose full stop".
--
Thoss