Oscar Ameringer, a principal leader of the socialist movement on the Southern Plains, was born in Achstetten, Germany, on August 4, 1870, the son of a cabinetmaker. Evading military service, he emigrated to the United States in 1886 and earned his living as a furniture worker, salesman, painter, and musician. He joined the Socialist Party shortly after it was formed in 1901 and became editor of the , financed by the Brewery Workers Union. He reported on the general strike that tied up the port of New Orleans in 1907. The dockworkers' success there in forging a longterm biracial alliance reinforced Ameringer's commitment to both racial equality and industrial unionism.

After the strike's collapse, Ameringer moved to Oklahoma, where he quickly assumed a leading role in the Socialist Party. Although lacking a sizable industrial working class, Oklahoma boasted the nation's largest Socialist Party, polling close to a third of the statewide vote. On his first speaking tour in 1907, traveling by covered wagon and on horseback, Ameringer realized that Oklahoma's farmers, primarily impoverished tenants, constituted the party's major potential base of support. Ameringer stayed in dirt-floored tenant shacks and homes dug out of hillsides and saw human suffering at its most intense. The Oklahoma farmers' socialist commitment deeply impressed him. He praised their determination by recalling that the man who presided at his first speech had arrived soaked to the skin, having swum across a river in his only suit because the bridge had been washed out.

Ameringer was one of the most popular speakers at the weeklong socialist encampments, frequently held in Oklahoma from 1908 until the U.S. entry into World War I. Farm people numbering in the thousands traveled vast distances, often in covered wagons bearing red flags, to hear Ameringer and other socialist orators. In 1911 Ameringer polled 23 percent of the vote in a three-way race for mayor of Oklahoma City.

In 1910 Ameringer led the fight against Oklahoma's adoption of the so-called grandfather clause, which was introduced by the Democrats to eliminate black suffrage. His effort was opposed by a faction in the Oklahoma Socialist Party based in the Little Dixie section of the state, which resented Ameringer as an outsider and feared losing white supporters. In 1913 this faction assumed control of the Socialist Party in Oklahoma, and Ameringer moved to Milwaukee.

Although opposed to U.S. intervention in World War I, Ameringer advised Oklahoma farmers against launching the Green Corn Rebellion, an abortive uprising intended to force the government to end the war. The repression it precipitated, along with a decline in farm tenancy, caused the swift collapse of the Oklahoma Socialist Party.

Returning to Oklahoma City after the war, Ameringer published a radical newspaper, the , which, as the from 1931 to 1941, developed a national circulation. Ameringer waged a high-profile campaign in the against the Ku Klux Klan, which was highly influential in Oklahoma during the early 1920s. From 1922 to 1931 Ameringer also published the in Oklahoma City, an insurgent newspaper that challenged John L. Lewis's control of the United Mine Workers. He contributed a column under the pseudonym Adam Coaldigger. In his preface to Ameringer's 1940 autobiography, , Carl Sandburg, an old socialist comrade and friend, compared him as a humorist to Mark Twain and Will Rogers. Oscar Ameringer died in Oklahoma City on November 5, 1943.