United Mine WorkersOne of the groups in the forefront of the fight for collective bargaining in the early 20th century, the United Mine Workers of America was founded in Columbus, Ohio in 1890 by the merger of two earlier groups, the Knights of Labor Trade Assembly No. 135 and the National Progressive Union of Miners and Mine Laborers.
- Lattimer Massacre - Sept. 10, 1897. 19 miners were killed by police in Lattimer, Pennsylvania, during a march in support of unions.
- Ludlow Massacre - April 20, 1914. 20 people, including women and children, killed when police and hired guns broke up a tent colony formed by families of miners who had been evicted from company-owned housing.
- Matewan, West Virginia - May 19, 1920. 12 men were killed in a gunfight between town residents and the Baldwin Felts Detective Agency, hired by mine owners.
The union's more recent history has sometimes been marked by internal strife and corruption, including the 1969 murder of Joseph Yablonski, a reform candidate who lost a race for union president against incumbent W.A. (Tony) Boyle. Boyle was later convicted of ordering the murder.
Automation and a general decline in American unions have cut heavily into the UMW's membership since World War II. In 1998 the UMW had about 240,000 members, half the number it had in 1946. It represents about 42 percent of all employed miners.