Mines were built in the Trachsellauenen area in the upper valley beginning in the late 16th century. An iron smelter was built in Zweilütschinen (now part of Gündlischwand) in 1715 to process the iron ore from Trachsellauenen. However most of the money from the mines went to the noble landowners. The villagers remained very poor. In the 17th and 18th centuries the poverty was so widespread that many of the villagers joined mercenary regiments or emigrated. A majority of the emigrants moved to the Carolinas in the United States. Beginning in the late 18th century, foreign mountain climbers began to use Lauterbrunnen as a starting point for their expeditions into the nearby Alps. Initially the climbers stayed in the village rectory. However, as Lauterbrunnen's fame grew and with the completion of a road from Interlaken in 1834 and the 1890 Bernese Oberland Railway, more hotels were needed for tourists. As new hotels were built, other tourist infrastructure was also built in the village. They built cable cars to Mürren in 1891 and to Wengen in 1893. But the most significant piece of infrastructure was the Jungfrau railway which was built in 1912. The Jungfrau rack railway runs from Kleine Scheidegg to the highest railway station in Europe at Jungfraujoch. The railway runs almost entirely within a tunnel built into the Eiger and Mönch mountains and contains two stations in the middle of the tunnel, where passengers can disembark to observe the neighboring mountains through windows built into the mountainside. In 1909 the English brothers Walter and Arnold Lunn popularized skiing, curling and bobsledding at Lauterbrunnen. These winter sports provided a whole new group of winter tourists and converted the summer tourist industry into a year-round business. The tourist economy of Lauterbrunnen was devastated due to World War I and II and the Great Depression. However, following the end of World War II, tourism rebounded. Many new vacation homes and chalets were built along with ski lifts, chair lifts and a heliport.