In the middle of Bernie Sanders’s unexpected surge in the Democratic presidential primary, Missouri governor Jay Nixon echoed some folksy wisdom against him: “Here in the heartland, we like our politicians in the mainstream, and [Sanders] is not — he’s a socialist.’’

Nixon would no doubt be shocked to learn of his own state’s history with the red menace. In the early twentieth century, the Socialist Party of America (SP) boasted 135 locals in Missouri. In St. Louis alone, 24 of the city’s 28 wards had a local.

St. Louis was hardly an anomaly. For the first two decades of the twentieth century, the SP was deeply embedded in American life. In 1912, just eleven years after its founding, the party netted nine hundred thousand votes in the presidential election — 6 percent of the total. Across the country, Socialists won seats on city councils and in town halls. In workplaces from breweries to mines, Socialists served in elected union positions, and locals (and even entire internationals) passed socialist resolutions. Socialist periodicals, like the iconic Appeal to Reason, were among the most read publications in the country.