Portside

It started with a single tweet. “They’re killing us.” A cry of deep despair from a female journalist that needed no explanation for women in Argentina: Within weeks, hundreds of thousands marched in cities across the nation with a single purpose — to demand an end to the killing.

In recent years, there has been a relentless and harrowing succession of news accounts of women in Argentina killed with shocking violence, each new case crowding out the previous. Women set on fire by their male partners. Women killed and their bodies stuffed into garbage bags.

“I sent off that tweet in a fit of rage,” said Marcela Ojeda, a radio reporter whose nerves are raw from years of covering the fatal effects of Argentina’s seemingly unbridled male machismo. “I rush to interview the families of victims before the other journalists get there,” she explained. “And every day I have to report yet another woman or young girl victim of femicide. That day, there was another new case and I just flipped.”

The term “femicidio,” which encompasses the murder of women by domestic violence, in honor killings and in other categories of hate crime, has now entered our everyday language in Argentina.

“The cause is our country’s macho culture,” said Fabiana Tuñez, executive director of Casa del Encuentro, a women’s shelter.

Women’s rights advocates like her see a continuum between the deadly violence and supposedly harmless everyday sexism. It’s true that Argentine men feel entitled to deliver a public “piropo” — literally, a compliment; in practice, any lewd comment or wolf whistle — to any woman of their choosing. What may once have been a tradition of poetic gallantry has degenerated into crude catcalling and aggressive propositioning. Such routine street harassment is widely regarded as socially acceptable, a masculine right even.

“Deep down, all women like being told a ‘piropo,’ ” said Buenos Aires’s mayor, Mauricio Macri, a presidential aspirant, in a radio interview last year. “I don’t believe those who say they don’t.” At the time, his remarks made barely a ripple.

Ms. Tuñez’s nonprofit organization, which provides shelter for 200 victims of abuse every month, is the only source for figures on femicide in Argentina. According to its count, more than 1,800 women were victims of femicidal violence between 2008 and 2014. That works out to one woman killed at least every 36 hours.

The real numbers are believed to be far higher — and, the Casa del Encuentro believes, are rising — though no one can say for sure because, scandalously, the government does not collect the data. In a vast majority of cases, the victim knew the perpetrator intimately.

“Over 70 percent are killed by their husband or ex-husband, boyfriend or ex-boyfriend,” Ms. Tuñez said. “It can be dangerous being a woman in Argentina.”

María Eugenia Lanzetti, a 44-year-old schoolteacher, took out a restraining order against her husband and installed a panic button on her cellphone. That didn’t stop him from bursting into a classroom and killing her in front of her students by cutting her throat.

Corina Fernández had reported her husband to the police 80 times. One morning, he surprised her as she dropped off her daughters at school, shooting her three times at point blank range. Miraculously, she survived and, with two bullets still lodged in her body, saw him sent to jail.

Teenagers can be especially vulnerable. Angeles Rawson, age 16, disappeared on the way home from gym class. Her body was later found by a worker at a giant garbage processing plant outside Buenos Aires. There are so many stories like these that even such horrific details eventually blur into one another.

Ms. Ojeda’s tweet got a response from nine other female journalists who knew one another through social media. They decided to organize a demonstration in front of the Congress building in Buenos Aires, setting the date for June 3.

They expected the protest to be small, but after a celebrity campaign featuring the slogan “Not One Less,” the #NiUnaMenos hashtag went viral. Unwittingly, the group had plugged into a deep seam of frustration and fear among Argentine women.

Maitena Burundarena, a cartoonist and writer adored for her popular comic strip “Mujeres Alteradas” (Women on the Edge), read out a list of demands, including that the government actually implement a law, passed six years ago, designed to prevent violence against women. She also criticized the lack of official statistics. Without these, it is impossible to know how Argentina ranks in comparison with the rest of Latin America.

The government lacks the resources to deal with the epidemic of violence. The courts are underfunded and police lack training. So even reporting a crime to the authorities often ends up being another traumatic experience for victims of violence.

“The solution has to come from society, it won’t come from the state,” Ms. Burundarena said. “Not all men are like that, we have to win over the good ones, no right-thinking man can tolerate violence against women. But someone has to start teaching the ones who don’t understand it that women are not the property of men.”

Malena Pichot, a stand-up comedian and Internet celebrity whose YouTube channel has garnered over 33 million views, wages her own campaign against Argentine men’s macho behavior.

“It’s about power,” she said of the piropo. “It’s not even about trying to pick you up. They do it because they can.” Ms. Pichot sees the street harassment as part of a continuum. “People fail to understand that it is a form of violence,” she said.

The day after the march, the country seemed to awake with a new spirit. Official reaction was prompt. Argentina’s Supreme Court and the Human Rights Secretariat both announced task forces to collect data on violence against women.

That’s a start. More important, it has begun a long-overdue conversation. As Ms. Burundarena said, “It suddenly became O.K. to talk about sexist violence.”