Folk singers Joan Baez and Bob Dylan perform during the March on Washington. (Photo by National Archive/Newsmakers)

We shall overcome, someday.

After that came Bob Dylan, Odetta, Peter, Paul and Mary, Marian Anderson, Josh White and the SNCC Freedom Singers, all raising their voices against racial injustice at the March on Washington.

While the Rev. Martin Luther King Jr.’s words changed history that afternoon, the songs surrounding it epitomized a decade of politically charged pop music that gave a soundtrack to the civil rights movement and rebuked the war in Vietnam.

But nearly a half-century later — with unpopular wars quietly raging overseas and end-times economic panic blaring at home — protest songs seem to have lost their power, potency and appeal. How did this happen?

It’s a long, slow fade that British author Dorian Lynskey tracks in his recent book “33 Revolutions Per Minute: A History of Protest Songs, From Billie Holiday to Green Day.” Chapter by chapter — 33 in all — Lynskey examines the work of Nina Simone, Gil Scott-Heron, the Clash, Bruce Springsteen and others who made fire at the intersection of music and activism.

But in the tome’s epilogue, the author wonders if he’s actually written a eulogy for the protest song. “If it is a eulogy, it’s a eulogy for the idea of the mainstream protest song,” Lynskey says over the phone from London, “the undeniable mainstream protest song which soundtracks certain events and maybe even changes people’s minds.”

Somehow, mind-changing, mainstream protest songs don’t seem to have survived into the 21st century. But those who say protest music itself is dead may not be paying very close attention.

“They aren’t listening,” says Tom Morello, former guitarist of Rage Against the Machine. “There may have been more unity around a song like ‘We Shall Overcome’ at the height of the civil rights movement, there may not be that one global, unifying anthem, but certainly there are strands of protest music now that are a vital part of today’s fight for justice.”

On Tuesday, Morello will release his second solo album of protest songs under the name the Nightwatchman, making him one of countless contemporary artists meshing music with protest. But he’s peddling it to an America that’s grown dubious of superstar musicians flexing their political muscles — or lack thereof.

During George W. Bush’s presidency, the outrage of our rock stars consistently failed to register in our earbuds. Neil Young, Radiohead, Erykah Badu, Pearl Jam, R.E.M., Bright Eyes, Pink, the Beastie Boys and many others wrote well-publicized songs opposing Bush’s policies and the war in Iraq.

But ask someone on the street to try and hum one.

Public Enemy’s definitive 1989 hit “Fight the Power” might have been the last great, galvanizing American protest song. Sonically innovative and lyrically trenchant, it arrived at the end of a decade when musical activism felt more like celebrity do-gooding. “We Are the World” and Farm-Aid were noble causes, no doubt, but they fostered a certain distrust of artists who were seen as merely burnishing pious images.

The chain is broken?

Twenty-five years earlier, protest singers still had America’s trust. “With the possible exception of Peter, Paul and Mary, they really were not making money of out of this,” says Dick Weissman, author of “Talking ’Bout a Revolution: Music and Social Change in America.” “But when you’re making hit records singing about revolution, you kind of get to the absurdity of Mick Jagger singing ‘Street Fighting Man.’ I mean, Mick Jagger has probably never been in a street fight in his entire life.”

When “Fight the Power” was released, Public Enemy wasn’t a group of stars who had suddenly developed a political stance; it was a group with a political stance that made the member stars. And they were part of a lineage.

“The tradition of writing protest songs was handed down informally,” says Lynskey. “If you were of Dylan’s generation, you could look back to Woody Guthrie and Pete Seeger. If you were a punk, you could look back to the angrier records of the late ’60s, as Joe Strummer did. If you were a rapper like Chuck D, you could look back to James Brown and Curtis Mayfield.” But after Public Enemy, Lynskey says, “that chain kind of stops.”

Now, protest music has been almost completely filtered out of the mainstream. You have to seek it out.

“ ‘A Change Is Gonna Come’ or ‘Gimme Shelter’ or ‘Living for the City’ . . . you didn’t have to go looking for them,” says Lynskey. “You’d turn on your radio at a certain point, especially in the second half of the ’60s and the first half of the ’70s, and you’d just hear those records.”

And while the boomer generation holds onto those songs, they can’t stand in for today’s activists.

“Frankly, I was tired of hearing ‘We Shall Overcome’ at these rallies,” says Morello. “We need songs that are written for this struggle in 2011, not just go back into the greatest hits of social-justice jams from the 1960s.”

Political LOLcats

Protest singers — Anne Feeney, Chris Chandler, John Trudell and Washington’s own Mary McBride among them — are still abundant in America, but they work in the margins. Meantime, in the global pop mainstream, protest sentiments appear in swatches and fogs. Political lyrics still bubble up in the verses of countless rappers, but they rarely fuel an entire song. And in England, rapper M.I.A.’s music still smacks of geopolitical confusion, while rock singer PJ Harvey’s new album, “Let England Shake,” is a purposefully cloudy meditation on war and empire.

If tomorrow’s protest music becomes more direct, it will still have to overcome colossal odds. In a digital era, instead of rallying around music, a new generation is rallying around social media.

“There are Facebook groups. There’s an angry tweet. There’s a comment on a newspaper Web site,” says Lynskey. “So that kind of pent-up, ‘how can I be heard?’ feeling? You can be heard, now.”

But your voice might be fleeting. Lynskey cites Kanye West’s controversial 2005 declaration that “George Bush doesn’t care about black people” during a live charity telecast for Hurricane Katrina survivors as an example of viral media’s potency and ephemeremality. “I thought, this is the way to do it now,” Lynskey says. “But I think there’s also a danger. . . . They’re the political version of LOLcats.”

Billy Bragg, the British protest songwriter, says that music still has a role in protest culture. “An expression of communal outrage, you don’t really get that from the Internet,” he says. “Five thousand people might ‘like’ your comment, but it’s not quite the same of being able to punch the air together” at a concert.

With England still confounded by a wave of riots that erupted in North London earlier this month, Bragg sees a huge opportunity for the next generation of protest musicians.

“If ever there was a time for people between the ages of 15 and 25 to speak to us and to explain something to us that we don’t understand, it’s now,” he says. “And I’d argue that music is the best forum to do that. Because it’s their forum.”

Meantime, here in the States, the most popular protest singer of our time may be hiding in plain sight, beneath a mountain of hype and a dress made of raw meat.

“I used to say, ‘It would be great if someone like Lady Gaga produced a political record,’ ” says Lynskey. “And she kind of did!” He’s referring to Gaga’s recent hit “Born This Way,” which touts equal rights for the LGBT community.

Bragg agrees. “[Gaga] has much more to lose than me by stepping up, so I respect that,” he says. “What we’re lacking is a scene where everyone’s doing it.”