May 3
Four striking workers are killed, at least 200 wounded, when police attack a demonstration on Chicago’s south side at the McCormick Harvesting Machine plant. The Haymarket Massacre is to take place the following day - 1886
And this: May 3, 1886 - At the height of the movement for the eight-hour day, police opened fire in a crowd of workers participating in a general strike at McCormick Harvester Co. in Chicago. Four workers were killed and anarchists called a public rally the following day at Haymarket Square to protest the police brutality. The resulting violence – and executions that followed -- became known as the Haymarket Massacre. View an excellent website on Haymarket at
http://www.chicagohistory.org/dramas/overview/main.htmEugene V. Debs and other leaders of the American Railway Union are jailed for six months for contempt of court in connection with Pullman railroad car strike - 1895

Pete Seeger, folksinger and union activist, born in Patterson, N.Y. Among his songs: “If I Had A Hammer” and “Turn, Turn, Turn” - 1919
And this:

May 3, 1920 - A young anarchist printer, Andreas Salsedo, plunged to his death from a 14th story window of an FBI detention room in New York City. He had been arrested during the notorious “Red Raids” organized by Attorney General Mitchell Palmer and was being interrogated for printing provocative leaflets. The FBI claimed he committed suicide.
Labor history found here:
http://www.unionist.com/today-in-labor-history & here:
http://www.workdayminnesota.org/index.php?history_9_05_03_2011