The first popular biography of Eugene Debs, the railroad worker turned radical visionary whose leadership helped elect more than a thousand Socialists across the country during the Progressive Era and inspired generations of Americans to fight back against the power of the rich over our politics and our lives.

Before Bernie Sanders, before Zohran Mamdani, America’s favorite socialist was Eugene Debs.

There was a time, a little more than 100 years ago, when some 1,200 Socialists held elected office across the United States. Wisconsin had a Socialist congressman in Washington. Ministers in Oklahoma preached the gospel of “Christian socialism” at revival-style gatherings come summertime. And Eugene V. Debs—part working-class agitator, part radical prophet—received nearly a million votes when he ran for president from behind bars.

Even opponents would describe Debs as Christlike. Born in Indiana in 1855, he’d dropped out of school at fourteen to work on the railroad. He’d seemed a rising star in the Democratic Party: an optimistic moderate who urged respectability and compromise. But this was the Gilded Age: an era of corporate tycoons and outrageous sums of money in politics, of grueling hours and few (if any) rights for workers. And when, in 1894, the president sent thousands of troops to break a railroad strike Debs had helped organize, he was radicalized. He emerged from a six-month prison sentence as a crusader, a stirring orator who would soon see all forms of unaccountable power—rich over poor, men over women, white over Black, colonizer over colonized—as poisonous to human freedom.

Cofounding the Socialist Party of America, Debs would spend the rest of his life striving to convince his countrymen that being an American and a socialist was the most natural thing in the world.

It wouldn’t be easy. He would suffer from chronic illness, lose friends, enrage allies, and risk his marriage. But he would also spark a profound shift in the American consciousness. Today, the ideals he spent his life fighting for are more popular than at any point since his death.

A rousing, poignant, intimately human tale of struggle against the odds, American Socialist is a stunning portrait of one man’s radicalization—and of the country he radicalized in turn.