Anthracite ­ or as some call it, "hard coal" or "black diamonds" ­ is made up almost entirely of pure carbon, causing it to burn cleaner and longer than bituminous coal. This discovery of anthracitešs potential spurred investment in Northeast PA and inspired technological advancements and transportation developments. In the 1820's, canals emerged as the primary means for shipment of coal to markets in eastern U.S. port cities. By 1842, and continuing well into the 20th century, the railroad reigned supreme in anthracite commerce. The expansion of anthracite mining and related transportation industries also resulted in a significant demand for labor, bringing waves of European immigrants to settle in the valleys and mountains between the Lehigh and Susquehanna Rivers. The area was dotted with "patch towns" to house English, Welsh, Irish, Polish, Ukrainian, Russian, Slovak, Lithuanian, and Italian miners and their families. Struggles between labor and management would soon follow­ including the violence of the famous Molly Maguire era ­ and would bring the Coal Region to the forefront with some of the earliest efforts to develop miners' unions. Initiatives conceived here would birth the Workingmen's Benevolent Association and later, the development of the United Mine Workers.