JOHN YANG: On this final day of LGBTQ Pride Month, tight installment of our Hidden History series isn't about an individual.

It's about an episode, how the anti-communist paranoia that gripped Washington at the dawn of the Cold War led to an often overlooked chapter in LGBTQ history.

Fan by Senator Joseph McCarthy's headline grabbing claims fears of communist subversion led to the hunt for communists in the government.

MAN: Department of Justice officials had promised further arrest as the crackdown on suspected subversives gathers momentum.

JOHN YANG: McCarthy explicitly linked communism with LGBTQ people, and some even said they were the bigger threat.

The Red Scare had spawned the Lavender Scare the name taken from Senator Everett Dirksen his reference to gay men as lavender labs.

A 1950 Congressional investigation concluded that LGBTQ people were unsuitable for federal employment and posed a security risk because fear of exposure made them susceptible to blackmail.

Thousands of workers across the government were investigated, interrogated and forced from their jobs.

Over time society's attitudes towards LGBTQ people changed but until 1975, they were still barred from the civil service.

And it wasn't until the 1990s that President Bill Clinton ended official discrimination based on sexual orientation for all non-military government workers.

Marc Stein is a history professor are at San Francisco State University.

Marc, for someone who's younger than a baby boomer in certainly in probably the age of your students may see all the celebrations that we've had during this Pride Month and wonder where that the attitudes wonder about the attitudes that led to this in the 1950s and early 1960s.

How do you explain it?

MARC STEIN, San Francisco State University: Well, it's complicated.

But I think most historians believe there were really three pillars of anti LGBT Animus.

Throughout the 20th century, one was religion that regarded homosexuality and gender transgression as a sin.

One was law and the state that regarded those expressions as criminal behavior.

And then there were science and medicine and psychiatry, which regarded homosexuality and transgenderism as signs of illness and sickness.

And so you put those three together, you have immense cultural authority, political authority, coming down hard on LGBTQ people.

JOHN YANG: What was it like to be an LGBTQ person who's working in the government at this time?

MARC STEIN: Well, for those who were in Washington, DC, there was a developing vibrant community based culture in bars and parks in parties.

And so, one could have a relatively full and interesting and dynamic, private life.

But the workplace was a different story.

And if you worked for the federal government in Washington, DC or elsewhere, there was the ever present threat that you could be outed, that you could be threatened.

And this affected more than just people who identified as LGBTQ, because even rumor or innuendo say if a person wasn't married, or didn't go out after work and behave in conventionally straight ways.

That could cast a pall of suspicion even on workers for the federal government who did not identify as LGBTQ.

JOHN YANG: As we said, one of the rationales that government officials offered for this was security risks.

They're the susceptibility of blackmail.

But in an ironic way, didn't the some government officials actually sort of prove that case about being able to coerce or coerce federal workers.

MARC STEIN: Yes.

So you know, while there is limited evidence that there were instances of blackmail, from external actors, what you say is absolutely true, that oftentimes the worst forms of blackmail came from within the federal government.

And so the threat of being outed in the workplace could itself lead to a form of blackmail, within the workplace.

JOHN YANG: Why do you think this episode may have been forgotten it largely by now?

MARC STEIN: Well, for decades, there was really intense censorship on the teaching of LGBTQ history, in public and private schools in the United States.

Certainly, when I was growing up in the 1960s, 1970s, and into the 1980s, there was little or nothing ever said about LGBTQ history.

And so in part, I think this has been forgotten for that reason.

Also, during the era itself, there were there were euphemisms there were non-explicit ways of talking about this phenomena.

So there might be discussions of perverts of deviance of misfits.

And so that wouldn't necessarily be understood or interpreted by the broad population as referencing LGBTQ people.

JOHN YANG: A lot of these policies were on the books maybe not observed, but they were still official policies until the 1990s and the early 2000s.

Why did it take so long to change?

MARC STEIN: Well, I think actually, we're still living with the legacies of those policies today.

And maybe that's something we can also talk about, but the for the earlier decades, those three pillars of anti LGBTQ oppression, religion, the state and science continued to exhibit many of those same attitudes for decades.

And so it wasn't until 1973 that the American Psychiatric Association declassified homosexuality as a mental illness, and even after that the APA continued to regard as illnesses, gender identity dysphoria or sexual orientation disturbance, and the other two pillars continued to express intense anti LGBTQ animus even after the official policies changed on civil service employment.

JOHN YANG: And talk about some of the legacies that you feel we're still living with from this.

MARC STEIN: Well, while it's no longer officially acceptable to refuse to hire someone for a government work, federal government work or to fire someone for federal government work based on sexual orientation and gender identity.

There's still a lot of artificial discrimination that goes on.

And we still see the traces.

I think the legacies of those earlier policies in things like banning the teaching of gender and sexuality in public schools, which a number of states have done in recent years, and we still see it, I would say in the refusal of many public schools and private schools to teach LGBTQ history, it's as if this is just an unacceptable topic, inappropriate for children.

And in that way, that form of censorship and repression really is working against fuller democratization, fuller openness and fuller educational excellence.

JOHN YANG: Mark Stein of San Francisco State University.

Thank you very much.

MARC STEIN: Thank you.