1 Mary Harris "Mother" Jones was born in 1830. The renowned labor organizer, who lived to be 100, said, "I live in the United States, but I do not know exactly where. My address is wherever there is a fight against oppression. My address is like my shoes; it travels with me. I abide where there is a fight against wrong."

1 In 1888, 19 machinists at the East Tennessee, Virginia, and Georgia railroad assembled in a locomotive pit to decide what to do about a wage cut. They voted to form a union, which became the International Association of Machinists.

1 May Day, or International Workers' Day, which commemorates the historical struggle of working people around the world.

3 In 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. As the peaceful protest drew to a close, a bomb was thrown into the police line. One officer was killed and several were wounded. Police responded by firing into the crowd, killing one and wounding many. The incident kicked off an intensive campaign against labor leaders and other activists, and eight anarchists were later framed for the bombing.

16 In 1938, the U.S. Supreme Court issued the Mackay decision permitting employers to permanently replace striking workers. Employers used this weapon against striking workers sparingly until the 1980s, when its use increased under the influence of the Reagan Administration's anti-union policies.

18 In 1917, the Amalgamated Meat Cutters and Butcher Workmen initiated a huge organizing campaign in packinghouses across the U.S. that brought membership from 6,500 to 100,000 two years later.

19 In 1942, the Steel Workers Organizing Committee formally became the United Steelworkers of America (USWA).

25 In 1886, Philip Murray was born in Blantyre, Scotland. He was the USWA's founding president and head of the Congress of Industrial Organizations from 1940 until his death in 1952.

26 Henry Ford's opposition to collective bargaining was in evidence on this day in 1937, when company goons attacked United Auto Workers (UAW) organizers at the "Battle of the Overpass" outside of the River Rouge plant. Though General Motors and Chrysler signed collective bargaining agreements with the UAW in 1937, Ford held out until 1942.

27 In 1959, delegates of the Insurance Agent's International Union and the Insurance Workers of America, having ratified the merger agreement at their respective conventions, convened as delegates of the merged union, the Insurance Workers International Union. The 15,000-member union merged with the United Food and Commercial Workers in 1983.

28 In 1835, the Ladies Shoe Binders Society was formed in New York.

30 Anniversary of the Memorial Day massacre at Chicago's Republic Steel plant in 1937. Police attacked strikers, killing seven, wounding 100.