I'd like to know if it was the McCarthy era or prior to that when the US became so anti-communism/socialism, so in order to make this a question, was it McCarthyism or something prior to the red scare that started the trend?

Grandparents and parents were pretty scared of what happened with "communism". Stalin, Mao, Pol Pot... Castro begging Khrushchev to nuke us. Mao rebuffing Khrushchev on threats on nuclear war (so we lose a million), Mao not caring about worldwide nuclear devastation because he thought communism would rise from the ashes. Stalin killing millions, Mao killing millions, Mao starving millions. North Korea starving millions.

Still a lot of folks around who lived through this stuff. Heck, I was doing air raid drills in the early 70s at school.