 Monessen experienced rapid growth in the first two decades of the twentieth century, the population increasing from 2,197 in 1900 to 11,775 in 1910 and then to 18,179 in 1920.While there were many companies operating in Monessen, the largest employer was Pittsburgh Steel Company, later renamed Wheeling-Pittsburgh Steel.In a practice that is shocking by today's standards (and not limited to Monessen), pay was determined by ethnic background.