 The Bergische industry ordered more and more coal from the new coal mining area along the Ruhr.Impressive and expensive railways were constructed through the hilly Wupper region, to bring coal, and later steel, in from the Ruhr, and for outward transport of finished products.By 1850, there were almost 300 coal mines in operation in the Ruhr area, in and around the central cities of Duisburg, Essen, Bochum and Dortmund.