Six months after the grisly disappearance of 43 teachers’ college students in the troubled Mexican state of Guerrero, friends and family of the missing spread out across the United States and Mexico to remind the world that the search isn’t over.

Marches took place throughout Mexico, and three caravans made up of the family and friends of the students and activists are traveling to at least 30 US cities to raise awareness about the case and ongoing disappearances here.

“Nothing will change if we stop fighting,” says Omar Garcia, who was with his classmates in Iguala before they disappeared on Sept. 26.

Mr. Garcia and a handful of other students were able to flee before his peers were taken by local police and handed over to a gang, according to government accounts. The gang then allegedly burned the bodies beyond DNA recognition. Six months later, only one student has been confirmed dead by investigators.

“This fight is for all Mexicans,” Garcia says by telephone from Saint Louis, Mo., where he’s traveling with the Caravana 43. “We are trying to take the problems of our country like corruption, government ties to drug cartels, and disappearances to a national and international level.”

Tens of thousands of people have disappeared in Mexico since 2006, leading to a wave of small-scale battles for truth and broader victim’s rights movements. But few have seen the sort of sustained action and awareness that exists now, observers say. Calling attention to suspected disappearances or kidnappings in Mexico can lead to the death or kidnapping of those searching for their missing loves ones.

But the families and friends of the 43 students have not been deterred from their quest for answers. The combination of a history of social mobilization in the state of Guerrero and the shocking circumstances of their case – not to mention their power in numbers – has helped bolster the movement.

“The families aren’t backing down,” says Ignacio Irazuzta, a sociologist at the Monterrey Technological Institute in Monterrey. They’ve initiated their own search for their missing sons, brothers, and nephews, hiring outside investigators, demanding answers from the government, and fighting for access to military barracks, where they fear the young men may have been taken.

“They’re internationalizing this idea of a disappeared person,” Mr. Irazuzta says. “And locally the case and movement has crystallized an opposition to the government.”

‘GREATER CREDIBILITY’

A few thousand people marched down Mexico City’s Reforma Boulevard Thursday evening.

Protestors carried signs and banners, with one reading simply, “six painful months have passed.” Another read, “No one can shut us up,” a reference to both the incessant search for the missing students and the recent firing of a prominent investigative journalist.

So far, the families of the missing students have done a great job bringing attention to their case, says Zara Snapp, the former advocacy director for the Mexican Commission for the Defense and Promotion of Human Rights, which works with relatives of missing persons to promote better laws and build support networks.

“There are so many families involved that the movement can be in many places at the same time,” says Ms. Snapp.

Including the six-month anniversary marches across North America, relatives have gone to multinational institutions like the Inter-American Commission on Human Rights and the United Nations’s Committee on Enforced Disappearance.

The state of Guerrero, where the students disappeared, has a long history of government repression – and social mobilization. In the 1960s and ’70s, state forces killed hundreds of suspected leftist-guerrilla fighters during Mexico’s dirty war, according to a recently released truth commission report. Guerrero is often at the center of large-scale teachers’ strikes and other union protests.

Alberto Díaz-Cayeros, a senior fellow at the Center for Democracy Development and Rule of Law at Stanford University, says the state’s history plays a role in how determined and organized the families have been.

“There’s an aura of greater credibility because this is not just a domestic political issue, but a more universal moral claim,” says Mr. Díaz. “This was a very specific group of students that were politically active and politically aware, in a place that has suffered repression historically.”

Relatives are calling for the government to return the missing students alive. It’s a tragic request given the time that’s passed and the gruesome acts drug cartels in Mexico have proven they’re capable of.

“There’s still no closure. No proof of death,” says Snapp. “Until there’s independent DNA identifying each student, they won’t accept their loved ones are gone. It’s a lack of trust.”

For its part, the Mexican government has repeatedly asked the country to move forward and largely ignored continued criticism about its slow response to the events in Iguala.

In a January speech, President Enrique Peña Nieto said, “I’m convinced that we should not remain trapped in this instant, this moment in Mexico’s history, of sorrow, of tragedy and pain. We just can’t dwell here.”

‘MOVING FORWARD’

Inevitably, the turnout at marches is going to start to decline as other news events and human rights violations emerge, Snapp says. Already, Mexico City marches are visibly smaller than ones in months past. Various banners on Thursday called for action on separate social causes, like water rights and freedom of the press.

“The families will need to figure out what their strategy is moving forward,” Snapp says. “The gravity of the case, the lack of access to justice and lack of closure” make these disappearances and this fight stand out, she added.

Mexico has seen victim’s rights movements in the past. Four years ago, the Movement for Peace with Justice and Dignity galvanized the often-isolated population of Mexicans who lost someone to drug violence or enforced disappearance. This group, too, organized a caravan to Washington, DC to call for awareness in the US. It was also pivotal in pushing for the 2013 General Law of Victims. Groups like this laid some of the groundwork for the families of the 43 students. Now there’s hope that they can work together to keep victims rights issues and attention on enforced disappearances in the public conscious.

Estimates of how many people have disappeared between 2006 – when then President Felipe Calderon declared war on drug traffickers – and 2012 vary widely. Government statistics put the number close to 14,000, while human rights groups say as many as 45,000 have disappeared. But disappearances also happen without recourse on the US-Mexico border.

For Garcia, the surviving student, this fight won’t stop until the families have answers from Mexico’s government.

“We are knocking on doors around the world, saying, ‘Do something. Put some pressure on Mexico. We need our human