Under John L. Lewis, the United Mine Workers (UMW) became the dominant force in the coal fields in the 1930s and 1940s, producing high wages and benefits. In 1914 at the peak there were 180,000 anthracite miners; by 1970 only 6,000 remained. At the same time steam engines were phased out in railways and factories, and bituminous coal was used primarily for the generation of electricity. Employment in bituminous peaked at 705,000 men in 1923, falling to 140,000 by 1970 and 70,000 in 2003. UMW membership among active miners fell from 160,000 in 1980 to only 16,000 in 2005, as coal mining became more mechanized and non-union miners predominated in the new coal fields.