Use the preferred English spelling indicated in Getty Thesaurus of Geographic Names.
Spell out names of states and US territories and possessions when they stand alone or follow a county name. Use postal abbreviations in references, addresses, or product identification.
SAS for Windows version 9.2 (SAS Institute Inc., Cary, NC, USA)
Abbreviate US and UK as adjectives; write out as nouns. When using in a location or address (e.g., affiliations), use USA and UK.
US citizens, citizens of the United States
Use accent for Réunion Island, no accent for Reunion state (Getty Thesaurus of Geographic Names).
United Kingdom: For England, list only “City, UK.” For other countries, list “City, Country, UK”
Cardiff, Wales, UK
Glasgow, Scotland, UK
For manufacturer locations, abbreviate state/province for all countries.
NSW (New South Wales)
WA (Western Australia)
See References for a list of cities that can be used without the state or country name in reference lists.