Clara Lemlich Shavelson was a leader of the Uprising of 20,000, the massive strike of shirtwaist workers in New York's garment industry in 1909, where she spoke in Yiddish and called for action. Later blacklisted from the industry for her labor union work, she became a member of the Communist Party USA and a consumer activist. In her last years as a nursing home resident she helped to organize the staff.

The New York shirtwaist strike of 1909, also known as the Uprising of the 20,000, was a labour strike primarily involving Jewish women working in New York shirtwaist factories. It was the largest strike by female American workers up to that date. Led by Clara Lemlich and the International Ladies' Garment Workers' Union, and supported by the National Women's Trade Union League of America (NWTUL), the strike began in November 1909.