Waves of European immigrants poured into Gillespie in the eighteen eighties to work its coal mines, and in the early nineteen hundreds the Chicago and North Western Railroad opened four mines to fuel its locomotives, with locals identifying the towns by mine number: Eagerville, Number one; Sawyerville, Number two; Mount Clare, Number three; and Wilsonville, Number four. The Little Dog Mine operated here from nineteen eighteen to nineteen sixty-eight. Although the mines later closed, Gillespie continued to celebrate this heritage each June with Black Diamond Days. During the Great Depression, miners' wages dropped because of low coal demand, and in nineteen thirty-two workers picketed and organized the Progressive Miners of America Union at a Gillespie convention. Over the next four years, twenty-one members were killed during conflicts, and their struggle was memorialized in nineteen thirty-six with the Mother Jones Monument at Union Miners Cemetery in nearby Mount Olive. Miners worked in perpetual darkness under the constant threat of cave-ins, gas explosions, and the inhalation of coal dust and methane. During the last century, one hundred thousand coal miners died in America, including more than four hundred in Macoupin County.