WI.
Michigan and Ohio. I learned it in Illinois. It’s definitely a WI/IL/IN/OH/MI game.
From Wisconsin, but Euchre wasn’t big at least with people I knew. Sheepshead was popular with some of my acquaintances (never learned it myself)
Brian
I associate it with books. People in books sometimes play euchre. Never played it in real life or know anybody who does.
I don’t associate it with a state, I associate it with college. But I’m from Michigan, and every college I played it at was in Michigan, so I guess I’d have to answer Michigan if a gun was pointed at me.
A lot of people play cribbage. Even my parents in Montana had a cribbage board.
I associate Hearts with college. That’s what we played at the University of Minnesota.
Same here. When I moved into the Cincinnati area after living most of my life in the Northern VA area outside Washington DC, it was the first time I’d ever heard of it. It’s a good card game, too. Like a truncated version of Spades with variable trump.
I immediately thought of Michigan.
Michigan, and very popular in Indiana and Ohio but I identify it as a MI thing.
Specifically, a white people Michigan thing, at least in the south-eastern part of the state. Random group of white people playing cards=euchre, random group of black people playing=spades.
Michigan and Wisconsin, definitely.
Cribbage is by far my favourite card game. I learned it in Michigan. 8)
Huh…my gut response was Michigan, because I vaguely recalled it being a part of Michigan Rummy, which I used to play as a kid in upstate New York. Now that I look, it’s got nothing to do with that game at all, but I would’ve gotten the Feud points anyway. Weird.
ETA: And as for cribbage, I’ve got a group here in Virginia that plays it quite often, inspired by my (San Diego native) dad.
Indiana?
I don’t know very many people from euchre-playing states, but I have cousins in Indiana.
michigan.
Michigan
C’mon up here. ‘Round here, we’re born with cribbage boards in our tiny lil’ hands. Truly, some of my earliest memories are huge cribbage tournaments at our camp between my parents and grandparents and uncles/aunts.
I also play Cribbage and know plenty of players around my parts.
I’m from Michigan and always thought of it as a Michigan thing. We had Euchre tournaments in the dorm, still have them at family gatherings.
Well well. I learned it from one of those Hoyle branded computer games in my youth, as I recall. Played a lot with my dad for a while. Now I’d need a refresher course (same as for Euchre, sadly; I tended to play that something like once every few years).
Maybe I’ll see if there’s a NYC Cribbage Meetup Group or something. 
Wisconsin, of course.
(I must be in the front row…)
My father and his buddy also played cribbage with their wives.
I learned both games from my father.
But whereas my father always impressed upon me how Euchre was a MI/WI thing, he implied cribbage was kind of played all over, and was really big when he was in the Army.