My mom grew up in Manitowoc and always called it Trivers. I call it Two Rivers, but if I want to poke fun at her, I say Trivers.
And I call it Ray-seen.
I grew up in Racine and pronounce it ruh-SEEN, as does everyone in my family.
The fact that we have a bunch of people from Chicago checking in to say they’ve always heard it pronounced RAY-seen really just proves the other pronunciation is the correct one. 
New Berlin is pronounced New BUR-lin. As far as I know the pronunciation was changed during WWII. This cracks up a buddy that moved here from out of state every time he has to say it.
I have no idea about Trivers as I’ve only ever heard it as Two Rivers.
Here in Ontario, “Berlin” got renamed to Kitchener (after Herb Kitchener, a British war hero) during WWI. That showed those pointy-helmeted goons in the trenches! I bet Ludendorf cried when he found out.
xxxx
So I suppose you consider those folks in Lima, OH to be downright crackers, eh?
There’s a township in Michigan called Buena Vista, they pronounce it Bewna Vista, ack.
A main road in my Snowbird Mom’s northern town is named “Milan”-locals say it as “MY-lan.” I always pronounce it in the Italian idiom, “Mee-LAAN,” and she’s always asking me, “What road again?”
Kringle!
<< Nom, nom, nom! >>
It’s Ruh SEEN.
I’ve yet to hear any “native” from the area (I live in IL a couple of miles from the border) and have never heard anyone local here or in WI ever pronounce it any differently…
Nom nom nom is right. Mmm… cherry kringle…