[jyl]

The default is some version of “[State]-ians” unless the result is too awkward to pronounce or to write, for the locals.

Why is it New Yorkers instead of New Yorkonians or New Yorkians, but Oregonians instead of Oregoners?

I get why it isn’t Oklahomanians, too much of a tongue twister.

That’s for US states and cities. Not sure what the pattern is for global places. Londoner, Parisian, Berliner, Hong Konger, Venezian . . . most are -ian or -er.

When you get to countries, there’s even more variety of, I guess you’d call it entomology. American, British, French, Spanish, Chinese, Japanese, Thai, Brazilian, Mexican, German, New Zealander. Some -an, some -er, some -ese, some change-a-letter-in-the-country-name?