At the conferences’ helm, Ms. Frye delivered motivational lectures, typically ending with a call to action: “Once again I say this to you, my sisters and my brothers, if I could do that in the late ‘70s and early ‘80s, what is your excuse? You have no reason for staying scared. You have no reason for staying closeted. You have no reason for not being the true person that you are. This is our decade. Make it happen for you now.”

She had recently cleared some hurdles herself. She had rebuilt a relationship with her son, by then in his 20s, although the reconciliation lasted only about a decade. (Her son declined to be interviewed.) She had also undergone a removal of the testes, which reduces testosterone, and won the right to amend her birth certificate.

Ms. Frye never opted for full gender-reassignment surgery. Ahead of her time, she firmly believed that surgery did not “complete” a gender change and should not be imposed on transgender people to justify a legal gender change on identification documents. “For many years I have been about the business mostly of freeing our community from the legal need of the scalpel,” she said in a speech in the 1990s.

During that period, for personal and political reasons, she and others consciously adopted “transgender” as an umbrella term.

“We framed the relevant community as broadly as possible to make the case that we’re all in this together — not just transsexual people but people who cross-dress, butch lesbians, feminine gays and so on,” Mr. Minter said.

Mr. Minter himself was going through a transition that would prove useful as a bridge between the gay and transgender communities. When he joined the National Center for Lesbian Rights as a lawyer, he identified as female and lesbian. In the mid-1990s, he found himself a transgender man inside the lesbian rights movement — and kept his job.

This was at a difficult time, when gay groups were allowing transgender people to be excluded from statewide nondiscrimination laws “left and right,” said Lisa Mottet, deputy executive director of the National Center for Transgender Equality. Minnesota, in the vanguard, had included transgender people in 1993, but it was eight years before a second state, Rhode Island, followed suit. The tone was set on high. The Human Rights Campaign, the largest gay rights organization in the country, agreed to drop transgender people from the federal Employment Nondiscrimination Act when it was introduced in Congress in 1994. (The legislation failed then and has yet to win passage.)

“That started the war with H.R.C., and it was a war,” Ms. Frye said.

Afterward, Ms. Frye and a handful of others, notably Riki Anne Wilchins, who had founded a grass-roots activist group called Transsexual Menace, took matters into their own hands. They started a transgender lobbying day in Washington. They also found common cause with another frustrated group.

“In 1995, when I went to my first Creating Change conference,” Ms. Frye said, referring to the large gathering on gay issues, “the trans caucus and the bisexual caucus had a combined meeting and decided to carry each other’s water.”

On the West Coast, another branch of the movement was gelling. San Francisco’s Human Rights Commission produced a comprehensive report on discrimination against transgender people that served as a template for grass-roots groups across the country.

Also in San Francisco, Ms. Smith, horrified to learn of the stabbing death of a transgender woman named Rita Hester in Massachusetts, raised the topic in The Gazebo one night in 1998. She compared the case to the murder the previous year of another transgender woman, Chanelle Pickett. Nobody in the chat room had heard of Ms. Pickett.

“It struck me that we were ignorant of the scope of violence against our community,” Ms. Smith said.

She started a web project, “Remembering Our Dead,” shortly before the 1999 film “Boys Don’t Cry” created broad awareness of such violence by dramatizing the real-life story of a transgender man, Brandon Teena, who had been killed.

Ms. Smith’s web project grew into the International Transgender Day of Remembrance, which is observed every Nov. 20 across the country and around the world. Ms. Keisling calls it “our sacred holiday.” By the turn of the millennium, many thought it was time to professionalize the all-volunteer transgender movement. Ms. Frye was increasingly representing transgender clients in name-change and discrimination cases, merging her political and professional work. She was also starting to run out of steam, she said.

“And then Mara came along,” she said, referring to Ms. Keisling, who financed the creation of the National Center for Transgender Equality in Washington in 2003. “She had the courage to move to D.C. My wife didn’t want to, and all my political chits were here. So there was kind of a passing of the baton.” Barriers Fall

In 2003, George W. Bush became the first president to welcome an openly transgender person into the White House.

It happened during a reunion for his Yale class of 1968. Making her way through the president’s receiving line, a woman in an evening gown extended her hand. “Hello, George,” she said. “I guess the last time we spoke, I was still living as a man.”

Mr. Bush smiled and graciously responded, “And now you’re you,” according to the woman, Petra Leilani Akwai.

Most of the big transgender advocacy groups started during the Bush years: the equality center, the Transgender Law Center, the Sylvia Rivera Law Project, the Transgender Legal Defense and Education Fund, and the Center of Excellence for Transgender Health, among others. But they did not push for federal policy changes during Mr. Bush’s presidency, despite the momentum that was building for their cause. On local and state levels, they were winning new laws protecting transgender people from discrimination, and they had persuaded the major gay and lesbian groups — even the Human Rights Campaign — to take up their struggle. Still, they feared a backlash. And they were heartbroken in 2008 when the Human Rights Campaign breached their détente, once again making a political compromise to exclude transgender people from the federal Employment Nondiscrimination Act.

This time, though, Ms. Frye said, “the tide had finally changed.”

“The gay community went wild,” she continued. “Every state equality group was up in arms.”

When President Obama took office, advocates presented him with a long wish list of proposed changes in federal policy. And despite an initial reticence about publicly expressing support for transgender people, his administration opened its doors to them.

“Dozens of us have been at the White House dozens of times for meetings,” Ms. Keisling said.

In October 2009, a few months after Chaz Bono — the only child of the singers Sonny and Cher — came out as a transgender man, Mr. Obama signed a hate crimes law, the first federal legislation to recognize and protect transgender people. That required an act of Congress, but most of what followed were rule changes.

The State Department took a first big step, eliminating an outmoded requirement of sex reassignment surgery for people who sought to change gender on their passports.

Following the lead of the courts, the Equal Employment Opportunity Commission then ruled that antitransgender bias was a form of sex discrimination under Title VII of the Civil Rights Act.

Agency after agency, on federal, state and local levels, ordered explicit protections for transgender people and, in some cases, mandated insurance coverage for transition-related health care. Gay and civil rights groups increasingly fought transgender discrimination in court, sometimes with Justice Department support. Legally at least, barriers started falling away.

In 2013, after over a decade of badgering from transgender advocates, the psychiatric establishment formally reclassified gender identity disorder as a “condition” called gender dysphoria, removing the stigma of mental illness. The next year, Chad Griffin, president of the Human Rights Campaign, issued a formal apology, saying, “H.R.C. has done wrong by the transgender community,” and pledging “a new chapter.”