During the last decades of the 19th century industrial growth in Switzerland continued, aided by a national program of railroad construction. The expanding rail network, which included the 1882 opening of the Saint Gotthard tunnel, facilitated transalpine travel and increased the importance of Switzerland as a transportation center. With the help of the chief natural resource, hydropower, imported raw materials were transformed into high-quality products and shipped to the world. Switzerland has maintained this export-oriented pattern of industrial development to the present day.