It was present in the 60’s in Western PA. A couple of “Country Clubs” come to mind. I experienced it from teachers in elementary school too.
Our answer to “Country Clubs” for WASPS only was to start our own country clubs. It worked out nicely - better food.
Here’s a personal example of me, a Jewish guy going to a non-Jewish country club (I don’t know if the club had anything to do with any religion - just a country for anyone who could afford to join).
I went with a Catholic girl whose family was also part Jewish (owned a major pharmacy in my old neighborhood), and whose Jewish cousin became an important nun leader in her convent or church.
It was nice, and the host was Art Donovan, the famous Baltimore Colts football player. A really nice guy.
There were some parts of Baltimore where Jews were not welcomed, and they were white areas. Blacks treated us pretty well and we never had any problems with anti-Semitism in junior or senior high school.
Sometimes people are just “people” to those they meet. no pettigrees, no religious symbols, no nothing - just friendship and respect.
Those were the good old days from what we are experiencing today. My Jewish granddaughter can kick ass if need be (karate) but she also protects her all friends from people who pick on them. Maybe our first Jewish UFC champion, eh?