Paul Kuntzler, a gay activist in the District since the 1960s, at his apartment in Washington. (Bill O'Leary/The Washington Post)

Decades before rainbow flags were common adornments on D.C. homes — 16 years before the pride flag was even invented — Paul Kuntzler walked into a Columbia Heights apartment in March 1962.

He joined a roomful of more than a dozen men, gay men like him, who wanted what they considered to be basic rights. Most were older than his 20 years and had been ousted from their federal government jobs because of their sexuality.

Together, they formed the ­Mattachine Society of Washington, the city’s first gay and lesbian advocacy organization. Since that meeting, Kuntzler, 75, and these early activists have attended countless city meeting and protests, fighting for gay rights and racial equality.

At a time when the Donald Trump presidency has ushered in a new era of activism — bringing many first-time protesters to the Mall — Kuntzler is still out there. He wants others out there too, but he also urges a new generation of activists to pay attention to their local politics. If they can build coalitions locally, he says, they will have a stronger voice on the national stage.

“I’ve seen and experienced tremendous social change and improvements among all constituencies, especially on the coasts,” said Kuntzler, a retired advertising director for the National Science Teachers Association. “Social change will continue to happen.”

Kuntzler cues up a video of his late partner’s memorial service. (Bill O'Leary/The Washington Post)

Kuntzler participated in January’s Women’s March on Washington, carrying a sign that read “Donald Trump Is the Ugly American,” an ode to the 1958 novel “The Ugly American.” Since then, he has attended the March for ­Science and the Peoples Climate March.

He has remained involved in activism and D.C. politics for 40 years, regularly attending city meetings and protests in support of liberal causes while volunteering for political campaigns in the District and Virginia. The groups he helped establish decades ago, the D.C. Gertrude Stein Democratic Club and the Gay & Lesbian Activists Alliance, are still players in the local political scene.

Earl Fowlkes, president of the Gertrude Stein Democratic Club, said Kuntzler’s presence at the group’s monthly meeting serves as a reminder to younger members that the LGBT rights movement didn’t start with them.

“Almost everyone at the meeting is younger, and he continues to provide a context on why we still need the organization and what the organization has done to advance rights,” Fowlkes said. “He’s a living legend. It’s like having an oral history book right there. No one ever talks when he speaks. We just sit there in silence and awe.”

Kuntzler, a widower, lives in a Southwest Waterfront apartment surrounded by a worn-out bicycle — his main mode of transportation — and relics of his past. There are newspaper clippings from protests he joined, along with photos from his work on the D.C. congressional campaign of Frank Kameny, co-founder of the Mattachine Society and the first openly gay man to seek a congressional seat. (Kameny campaigned unsuccessfully to be the District’s nonvoting representative to Congress in 1971.)

There’s a framed proclamation hanging on his wall that then-Mayor Marion Barry signed, declaring April 9, 1981, as Paul Kuntzler Day in the District.

Kuntzler shares sentimental papers he has saved at his apartment in Washington. (Bill O'Leary/The Washington Post)

Also hanging in his bedroom is documentation of Kuntzler’s most unconventional interest: a copy of the $200,000, two-page New York Times ad he purchased in 2007, which asserted that Lyndon B. Johnson killed President John F. Kennedy in an “incredibly complex and brilliantly planned conspiracy” involving the FBI, in part, because Johnson “possessed an overpowering ambition to be president.”

Kuntzler remembers every date with precision, his memory serving as a chronicle of D.C. history.

He says he first traveled to Washington on “Tuesday, Jan. 17, 1961,” from his home town in suburban Detroit to attend Kennedy’s inauguration and discovered a vibrant gay community in the city. He moved to the District and met his partner of 40 years, Stephen Brent Miller, on “Friday, March 30, 1962” at one of the city’s few gay bars, the Chicken Hut.

In 1965, Kuntzler, Kameny and a handful of other activists participated in what Kuntzler says was the first gay rights demonstration in front of the White House. He made a poster that read, “Fifteen Million Homosexuals Protest Federal Treatment.”

Kuntzler attended the 1963 March on Washington for Jobs and Freedom on the Mall, and he said the Women’s March in January harked back to that historic day decades ago. The crowds. The progressive message. And, Kuntzler said, the feeling of hope he felt afterward.

“It was so successful and so peaceful that it made me hopeful that things would change for African Americans, for gay people, that the whole social change would come,” he said of the 1963 march.

Kuntzler, who is white, said leadership in the city’s black community played an early role in paving the way for advancements in Washington’s gay and lesbian movement. When the District got home rule in 1973, the reins of local government were passed from generally conservative white congressmen to longtime black leaders in the city.

Kuntzler began volunteering for Barry’s campaigns in the 1970s, calling him a champion for gay and lesbian rights who hired many openly gay men to his cabinet. He treasures a photo of Barry’s then-wife, Effi, in his home garden. (Barry, who died in 2014, voted against legalizing same-sex marriage as the Ward 8 council member in 2009. Kuntzler said most people remember Barry as a champion of gay rights and found this vote disappointing.)

“Black people as a group have been more supportive of gay rights than anyone else. That’s why we’ve made so much progress,” Kuntzler was quoted as saying in a 1979 Washington Post article.

The Gertrude Stein Democratic Club helped transform the local lesbian, gay, bisexual and transgender population into a persistent voting bloc. The club still endorses candidates every local election, and Kuntzler still attends every meeting.

David Catania, the first openly gay man elected to the D.C. Council, can’t remember when he first met Kuntzler, saying he’s always been part of the D.C. landscape. Kuntzler volunteered for many of Catania’s political campaigns, including his 2014 run for mayor as an independent.

“He’s one of the Founding Fathers of the modern LGBT movement in our city, just a real silent soldier,” said Catania, who joined the council in 1997 as a Republican. “I would never have been elected but for Paul and his contemporaries.”