In the 1870s, the city became a major hub of the Pittsburgh and Lake Erie Railroad. New Castle's population swelled from 11,600 in 1890 to 28,339 in 1900, and to 38,280 in 1910, as immigrants, particularly from Italy, flocked to the city to work in the mills and nearby limestone quarries. Italian laborers of the era were frequent victims of the Black Hand society, which employed blackmail and extortion to rob the workers of their pay. In 1907 the headquarters of the Black Hand for the entire region was discovered in the village of Hillsville a few miles west of New Castle. By this time New Castle was one of the fastest-growing cities in the country, and with the construction of the largest tin plate mill in America, the city became the tin plate capital of the world. The tin plate industry marked a new increase in the city's prosperity.