to one based on agriculture and wood extraction. The Mapuches' loss of land following the occupation caused severe erosion since Mapuches continued to practice large-scale livestock herding in limited areas. Crisis and restructuring (1914–1938) The opening of Panama Canal in 1914 caused a severe drop in traffic along Chilean ports due to shifts in the maritime trade routes. In addition to this international trade collapsed and state income was reduced to half of its previous value after the start of the World War I in 1914. The Haber process, first applied on an industrial scale in 1913 and later used as part of Germany's war effort due to its lack of access to Chilean saltpetre, ended Chile's monopoly on nitrate and led to an economic decline in Chile. While saltpetre mining gradually waned in importance copper mining rose, exporting raw materials to a level unprecedented in the history of Chile. By 1929 copper exports had reached the same values as saltpetre exports, and in 1937 the value of copper exports largely surpassed that of saltpetre. In the 1920–1937 period both industries had combined a 70–83% share of the value of Chilean exports. In the 20th century two new economic actors rose to prominence in Chile; the state and capital from the United States. Beginning in 1905 United States-based companies came to develop and control copper mining in Chile. The main companies were; Anaconda Copper in control of Chuquicamata, Kennecott Copper Corporation in control of El Teniente and Andes Copper in control of Potrerillos. Between the 1910s and 1930 United States investments in Chile had a tenfold increase, the bulk of which was directed to mining activities. The increased influence of the United States in Chilean economy did not only manifested itself in copper mining but also in foreign trade. After the First World War the United States became the prime importer of Chilean goods and in the 1930s it overtook the United Kingdom's place as the prime source of Chilean imports. Edwin W. Kemmerer, a "Money Doctor", was invited to Chile in 1925 to deal with monetary policy and inflation problems which were considered one of the principal economic problems of Chile at the time. The visit by Kemmerer was used to back up monetary policies already outlined by Chileans. These reforms included the creation of a central bank, the establishment of a government budget law and general bank law.