May 21

Italian activists and anarchists Nicola Sacco and Bartolomeo Vanzetti, widely believed to have been framed for murder, go on trial today. They eventually are executed as part of a government campaign against dissidents - 1921
 
The “Little Wagner Act” is signed in Hawaii, guaranteeing pineapple and sugar workers the right to bargain collectively.  After negotiations failed, a successful 79-day strike shut down 33 of the territory’s 34 plantations and brought higher wages and a 40-hour week - 1945
 
Nearly 100,000 unionized SBC Communications Inc. workers begin a 4-day strike to protest the local phone giant’s latest contract offer - 2004