>There are also rumours from some of the generals that the Fair Folk and orcs exist in the north

It's hilarious that there isn't a single mention of Michigan,the state that makes up their entire northern land border and achieved statehood through war with ohio.

Michigan is what's north of ohio, not canada, and would fight an invasion far too hard to just not mention it, if not defeat it completely and counter invade in retaliation but there's no mention of any transported territory north of them at all, there's nothing there, which means Michigan was left in the old world with canada,and maybe Alaska too.

Evidently this was the contiguous states with some of the northern border cut off,so back in the old world there would just be Michigan,Alaska,Hawaii and all the island territories...and whoever wasn't in the transported area at the time,including like 800 military bases,a bunch of naval assets like carrier groups and submarines,diplomatic institutions and so on.

So in the old world a huge chunk of the US population is suddenly made up of a huge chunk of the military and foreign service,and the normal line of succession to determine who's in charge only has one person in the top 20 or so that's from a state not effected,if they happened to be at home and the rest weren't abroad. To appoint her president would take an emergency constitutional amendment by 2/3 of congress or something though,since she born in canada and moved at age 4. Fortunately for the first canadian Michigan woman president of the United States,the remainder of congress(again if they were at home at the time) would consist of up to six senators with 2/3 being of the same political party,14 house members from Michigan and only 2 from each of the other two possibly remaining states, and 5 from territories that don't get a vote anyways.

TLDR You said Michigan wasn't there,so back home all the remaining global military power of the USA goes to Michigan.