Off the top of my head, I can’t think of a word in English that ends with “is” while being singular, only plurals and uncountables come to mind, so I can’t really follow the examples of other words. What makes it even weirder, I’m not sure how to pronounce Illinoises… Would it be as written, or as if an Illinois was pronounced by someone who has never encountered it before? Illinoi are also meh, since now plural looks as a singular and the other way round.
You speak like a second Illinois is inevitable. Is there something you know? Hands off Michigan, but Iowa and Wisconsin are fair game
I live in northwestern Illinois, Iowa can keep their independence for their cheap gas but we really should annex Wisconsin for their geography alone.