The victory of Alexandria Ocasio-Cortez over longtime Democratic congressman Joe Crowley of New York inspired some hysterical punditry. We were told that the 28,000 people that voted in a district of more than 600,000 had decided the fate of the political universe. Ocasio-Cortez, in this telling, heralds the coming of Democratic Socialist, multiracial, female-dominated America. The 28-year-old bartender and community activist is the Democrat of the future—according to no less an authority than the chairman of the Democratic National Committee. And in a polarized media climate, with hyperbolic insinuations of "civil war" and calls for the harassment of political opponents, one is tempted to believe that romanticism and extremism grow ever stronger.

I remain skeptical. For one thing, New York politics is sort of the equivalent of the Las Vegas party scene—what happens there tends to stay there. Crowley was boring and out-of-touch; Ocasio-Cortez is appealing and a tireless campaigner. Her picture of democratic socialism is all rainbows and unicorns, platitudes and aspirations. And the numbers involved in the primary were so small that randomness has to have played some part in her 4,000-vote win. Ocasio-Cortez is neither a threat to America nor to the American right. But she is representative of the transformation of the American left.

The only civil war happening at the moment is within the Democratic Party. The old-guard corporatists are under attack from activists with radical goals and immoderate tempers. You can trace a line from Occupy Wall Street in 2011 through Black Lives Matter in 2013 through Bernie Sanders in 2016 through the Women's March a year later, Tom Steyer and Maxine Waters's impeachment campaigns, the growing prominence of Democratic Socialists of America, and the movement to abolish Immigration and Customs Enforcement today.

How long Nancy Pelosi remains Democratic leader is an open question. During a recent telephone town hall, activists demanded Chuck Schumer stop President Trump's Supreme Court pick (he can't) and back up Auntie Maxine (he'd be crazy to). The intellectual energy is on the farther reaches of the left: Jacobin and n+1 are the hot journals, Chapo Trap House is the podcast the cool kids listen to, Washington Post columnist Elizabeth Bruenig defends the socialist ideal in Jeff Bezos's newspaper, and the New York Times recently announced that Michelle Alexander, author of The New Jim Crow, will be joining the op-ed page in the fall.

This is a trend that has been building for some time but over the last two years acquired galvanic force. Why? Is it because the nature of the threat that Donald Trump represents to the left? Is it because, as Victor Davis Hanson has argued, Trump denied the left the power it considers its due? Or is it because Barack Obama, despite all of his purple rhetoric and fantastic publicity, was unable even to approach his goal of "fundamentally transforming" America—because he left the Democratic Party a smoking ruin, and bequeathed a regulatory and policy legacy as fragile as a paper crane?

All of these explanations for the resurgent left have some merit. I am especially partial, naturally, to the one that pins responsibility on Obama, who raised the hopes of a generation that the waters would cease to rise only to hand over command of the ship eight years later to Donald Trump and become a Netflix producer. Still, it is important to recognize that the collapse of the center-left is not limited to America. It is a global phenomenon. Obama and Clinton may have broken the Democratic Party, but don't hold them responsible for the destruction of the French Socialists, the fall of the Italian Democratic Party, the takeover of Labor by Jeremy Corbyn, the worst result by the German Social Democratic Party since World War II, and the triumph of López-Obrador in Mexico.

If there is a common denominator to these electoral shakeups, it is the politics of migration. The overthrown establishments all benefited from the economics of illegal immigration and used migrants as chits in a humanitarian sweepstakes in which the leader who signals the most virtue wins. Migration became a symbol for the "flat world" of globalization where not just people but also cultures, goods, and investments flowed freely, borders had little meaning, and sovereignty was pooled upwards to transnational bureaucracy as identity was reduced to racial, ethnic, religious, or sexual characteristics. The fantastic wealth produced by the global marketplace enriched the center-left to such a degree that its adherents became walled off from the material, social, and cultural concerns of the working people they professed to represent. And so middle-class workers who believe a country's leadership ought to be accountable to a country's citizens went elsewhere—devastating the ranks of the center left and creating a vacuum for the neo-socialists of the twenty-first century.