For decades, democratic socialism was an old man's ideology. Its adherents were aging hippies, old-time union organizers, and folks who fondly remembered the pre-'60s left. As recently as 2013, the average member of the Democratic Socialists of America (DSA) was 68 years old. Even today, the ideology's best-known spokesperson, Sen. Bernie Sanders (I–Vt.), is 77.

But Sanders is suddenly an outlier. Today, most DSAers are young: The average member is 33. The ideology's second-best-known spokesperson, Rep. Alexandria Ocasio-Cortez (D–N.Y.), is just 29. And the DSA's ranks have grown larger as well as younger. Socialist gatherings buzz with youthful energy, and they are taking place all over the country.

This movement is flexing its political muscles, having helped elect a number of candidates to office—most famously Ocasio-Cortez, who has quickly become a prominent voice in Congress. The DSA has every intention of shifting the "Overton window" of American politics far to the left. And if we're not careful, it might succeed.

Despite his own advanced age—and even though he's not a member of the group himself— Sanders is by far the person most responsible for bringing this wave of young people into the DSA. His groundbreaking 2016 campaign for the Democratic presidential nomination helped spread socialist ideas to a generation born after the collapse of the Soviet Union.

"Bernie Sanders is who introduced me to socialism," says Alex Pellitteri, co-chair of New York City's chapter of the DSA's youth arm, the Young Democratic Socialists of America. "I was a Democrat, I was a liberal, but I had never really crossed that line to socialism."

Essentially, Sanders has done for democratic socialism what Ron Paul did for libertarianism in the late '00s: make it an exciting, cool, radical alternative to the mainstream parties' staid orthodoxies. Just as Paul challenged other Republicans' commitment to waging increasingly unpopular wars, Sanders slammed Democratic frontrunner Hillary Clinton for her Wall Street ties, her hawkish foreign policy, and her general lack of left-wing bona fides. Clinton won the nomination, but Sanders put up a much better fight than expected—a testament to the popular appeal of the ideas he was proposing.

Those ideas included a single-payer health insurance system, free tuition for all college students, a federal minimum wage of $15 an hour, and a more progressive tax system that confiscates wealth from the richest 1 percent and redistributes it to everyone else. Such proposals are particularly popular with younger Americans. According to a 2018 Harvard Institute of Politics poll, 55 percent or more of 18- to 29-year-olds support a $15-an-hour federal job guarantee, free college tuition, and Medicare for All. In a Harris Poll this year, 73 percent of millennial and Gen Z respondents thought the government should provide universal health care, and about half said they'd prefer to live in a socialist country. While Americans overall have a much more favorable view of capitalism than socialism, Americans between 18 and 24 do not: 61 percent have a positive reaction to the word socialism, compared to 58 percent for capitalism.

One reason for this is that people like Sanders have studiously worked to get a softer definition of socialism into circulation. Throughout the 20th century, the word evoked either the working class directly seizing the means of production or the government nationalizing industries, setting prices, and reducing or abolishing the right to own private property. The latter was much more common in practice, and the countries that took that route—the Soviet Union, mainland China, the Eastern European states, etc.—had horrific human rights records. Socialist regimes found it necessary to negate a whole host of individual rights and to arrest or murder dissidents in order to realize their ends.

But the founders of the DSA rejected Soviet-style socialism. They had more in common with the socialist parties of Western Europe, which established generous welfare states and sometimes nationalized industries, but which operated within the boundaries of a democratic political system, not a one-party police state. In 1962, future DSA founder Michael Harrington quarreled with the authors of the Port Huron Statement, a leftist student manifesto, because he felt they hadn't denounced the Soviet Union in strong enough terms. About a decade later, Harrington's former faction of the Socialist Party split off to form the Democratic Socialist Organizing Committee, which later merged with another organization to become the DSA.

When today's most prominent democratic socialists are asked to explain their ideology, they tend to skimp on the substantial structural questions and lean on paeans to dignity, generosity, and equality. Sanders has defined democratic socialism as "the understanding that all of our people live in security and dignity" and "a government and an economy and a society which works for all." Ocasio-Cortez defines it as "democratic participation in our economic dignity."

It shouldn't be surprising that democratic socialism, reduced to a set of pleasant-sounding buzzwords and some proposals to give more people free stuff, is having a moment.

And what a moment it is. "When Harrington died in 1989," The Nation observes, "his organization hadn't grown much beyond the 6,000 aging members it had had at its founding." After a quarter-century, the members were even more aged and little else had changed. The DSA's official magazine, Democratic Left, had 6,700 subscribers in 2016.

A year later, in the wake of Sanders' first presidential campaign, the magazine had more than 28,000 paid subscribers. By 2018, it had 46,000. The organization now claims about 50,000 members. Many of them are concentrated in New York City, but DSA chapters can be found in 180 towns across the country.

The success of democratic socialism is much broader than just one organization. The socialist magazine Jacobin, founded in 2010 by Bhaskar Sunkara, increased its circulation from 10,000 in 2015 to 40,000 in 2018. The socialist podcast Chapo Trap House, which debuted in March 2016, is now the second most popular account on the crowdfunding platform Patreon, and its hosts rake in an average of $123,500 in donations per month.

Democratic socialists have won electoral victories too. The DSA is not a political party and does not run its own candidates, instead endorsing Democrats and independents who it feels are sufficiently committed to socialism. (Sex and the City actress Cynthia Nixon, for instance, received the DSA's endorsement in her unsuccessful 2018 primary run against New York Gov. Andrew Cuomo.) In the 2016 and 2017 elections, DSA-backed candidates won a smattering of races around the country, including a seat in the Virginia House of Delegates. And in 2018, Ocasio-Cortez, a 20-something organizer and complete political unknown, won a stunning Democratic primary victory over incumbent Rep. Joe Crowley. She became an overnight sensation, and in the general election she was one of two DSA members to capture House seats. Rashida Tlaib (D–Mich.) was the other.

Ocasio-Cortez's savvy use of social media has generated tons of press coverage. She now has more Twitter followers than House Speaker Nancy Pelosi (D–Calif.). Conservative websites and cable channels love to pillory her, but that has only helped her become one of the most visible members of Congress.

Sanders is the only major 2020 presidential candidate to self-identify as a democratic socialist. But most of the Democrats have signed on to DSA-friendly policies. Sens. Kamala Harris (D–Calif.), Elizabeth Warren (D–Mass.), and Kirsten Gillibrand (D–N.Y.) have joined Sanders in backing Medicare for All. The Green New Deal, Ocasio-Cortez's pie-in-the-sky plan to tackle climate change while creating public works projects, has been endorsed by a host of candidates: Sanders, Warren, Harris, Gillibrand, Sens. Cory Booker (D–N.J.) and Amy Klobuchar (D–Minn.), and former Housing and Urban Development Secretary Julián Castro.

If the centrist standard-bearer, Vice President Joe Biden, wins the Democratic nomination, it will be a setback for the movement. But democratic socialists are not pinning all their hopes on the presidency, even as they work to install Sanders in the White House. They are patiently growing their ranks, expanding their influence, and increasing their cultural cachet.

So far, the strategy is working. If you assumed that socialism's appalling 20th century failures would relegate it permanently to the ash heap of history, you were wrong.