The integration of local labor markets into broader regional and national labor markets during the nineteenth century increased competitive pressures on wages and working conditions (Commons et al. 1918, pp. 43–4; Lebergott 1964, pp. 132–6). As the tendency for wage equalization documented in Chapter 5 illustrates, the scope for local variations in the terms of employment declined. In many industries, the competitive pressures caused by increased market integration were further compounded by technological changes that encouraged the increasingly fine division of labor and enabled employers to replace skilled craft workers with semiskilled operatives or unskilled laborers. The impact of these developments on American workers was profound. Broader labor markets and technological changes expanded employment opportunities for some workers, but for others they undermined efforts to increase wages and improve working conditions.

The increasing elasticity of labor supply resulting from the geographic integration of labor markets severely constrained unions' efforts to improve wages and working conditions. Having won higher wages and more control over piece rates in 1881, for example, carpenters in St. Louis found that “our advances in wages would soon be lost through the influx of men from cities where wages were lower. Day after day men came from other states where wages were $1.75 to $2” (quoted in Tygiel 1981, p. 366). A skilled butcher in Chicago put the matter more bluntly, observing simply that the threat of being replaced by less-skilled workers was “the club held above our heads at all times” (quoted in Tuttle 1969, p. 412).