(UMW), international labor union formed (1890) by the amalgamation of the National Progressive Union (organized 1888) and the mine locals under the Knights of Labor. It is an industrial union, including all workers in the coal industry. The lack of continuity of employment, the prevalence of company-owned towns, and the extreme occupational hazards have led to numerous strikes and constant efforts to improve conditions by collective bargaining.
Earlier unions of miners in the United States had been the American Miners' Association (founded 1860); the Miners' National Association of the United States of America (founded 1873); the Ohio Miners' Amalgamated Association (founded 1882), later to become (1883) the Amalgamated Association of Miners of the United States; and the National Federation of Miners and Mine Workers (founded 1885). The newly formed UMW affiliated with the American Federation of Labor (AFL). The UMW strengthened its position in 1894 and 1897 by successful strikes, and in 1898, under the leadership of John Mitchell, the fight for an 8-hour workday was won. A no-strike pledge was kept during World War I, but strikes in 1919–20 led to the establishment by the U.S. government of the Bituminous Coal Commission, which awarded the miners a substantial wage increase. In 1920 the anthracite operators recognized the UMW as a bargaining body.
John L. Lewis became president of the union in 1920, and under his militant leadership most of the union's aims were accomplished, including a health and welfare fund assuring a pension of $100 per month to all miners over 62. The UMW was a leader in the formation (1935) of the Committee for Industrial Organization (later the Congress of Industrial Organizations, or CIO) and was expelled from the AFL in 1937. In 1942, however, the UMW withdrew from the CIO. A strike (1943) during World War II brought about governmental seizure of the mines. Strikes in 1945–47, although successful, cost both Lewis and the union heavy fines for violation of the injunction barring the union from striking. The UMW was readmitted to the AFL in Jan., 1946, but was again disaffiliated in 1947, when Lewis refused to sign the non-Communist affidavit required by the Taft-Hartley Labor Act. Lewis resigned as union president in 1959, and his place was taken in 1960 by Thomas Kennedy, long a vice president of the UMW.
Upon the death of Kennedy, W. A. (Tony) Boyle was elected (1963) president. Throughout the 1960s, Boyle was increasingly criticized by a portion of the rank and file membership. Dissidents rallied to the campaign of Joseph A. Yablonski in 1969, but Yablonski lost to Boyle. A few weeks later Yablonski was murdered. In 1972, Boyle and other top union officials were convicted of making illegal political contributions with union funds. In the same year a federal judge invalidated the 1969 election, and Arnold Miller, a Yablonski supporter, defeated Boyle for the presidency. Miller immediately set about reforming the union by replacing Boyle appointees, stopping Boyle's pension, and reducing the salaries of union officials. In 1974 Boyle, charged with having ordered Yablonski's killing, was convicted of murder.
Since World War II, automation, the popularity of other energy sources, and the establishment of nonunion mining operations have produced a long-term decline in the union's power. Richard Trumka became head of the union in 1982, and in 1989 the UMW reentered the AFL-CIO. When Trumka became secretary-treasurer of the AFL-CIO in 1995, Cecil E. Roberts, Jr., succeeded him as UMW president. In 1998 the UMW had about 240,000 members, far below the half million members it had in 1946; a decade later there were only 105,000 members.