These led me to wonder if there are unwritten rules in English about how these demonyms are formed eg Washingtonian but not Washingtonite.
Sometimes they respect the name in the language in question eg Parisian, Amsterdammer, Berliner.
But when an English suffix is added to a non-European name you could have Cairoite or Cairoene or Caorinian, Bangkokian or Bangkokite.
Some British places still have Latin ones like Mancunian (Manchester) and Cantabrigian (Cambridge). These are also places in America. What are the adjectives there?
BlackGrey mentions a fair bit of cohesion regarding Canadian naming conventions. How far does it go generally?