Note, St. John's is given as an example when not to expand abbreviations on OSM Wiki (https://wiki.openstreetmap.org/wiki/Abbreviations); additionally, the city self-styles as "St. John's", legal and official local buildings, etc. use "St. John's", and the local (at city, provincial and country levels) convention is styled "St. John's". 

Another Atlantic Canadian city is "Saint John", New Brunswick; proper use of "St. John's" helps distinguish.
