Craig Miner, the main issues of progressive era Kansas (in chronological order), were the flood of 1903, conservation, the battle to control Standard Oil in 1905, regulation of railroads and trusts, capital punishment, women's rights, public health, urban reform, the Progressive Party campaign of 1912, and isolationism in foreign policy. In addition there was a long debate on the state purchase of school textbooks. The state wrote, printed and sold its school books until 1937. Supervision was lax and the textbooks were poorly done--filled with typos, grammatical errors, garbled passages and poor artwork. However, the state did save some money. According to Gene Clanton, Populism and progressivism in Kansas had similarities but different bases of support. Both opposed corruption and trusts. Populism emerged earlier and came out of the farm community. It was radically egalitarian in favor of the disadvantaged classes; it was weak in the towns and cities except in labor unions. Progressivism, on the other hand, was a later movement. It emerged after the 1890s from the urban business and professional communities. Most of its activists had opposed populism. It was elitist, and emphasized education and expertise. Its goals were to enhance efficiency, reduce waste, and enlarge the opportunities for upward social mobility. However, some former Populists changed their emphasis after 1900 and supported progressive reforms.ref> Gene Clanton, "Populism, Progressivism, and Equality: The Kansas Paradigm" Agricultural History (1977) 51#3 pp.559-581.</ref> The new city manager system was designed by progressives to increase efficiency and reduce partisanship and avoid the bribery of elected local officials. It was promoted in the press, led by Henry J. Allen of the Wichita Beacon, and pushed through by Governor Arthur Capper. By the 1980s 52 Kansas cities used the system. 1910s In 1915, the El Dorado Oil Field, around the city of El Dorado, was the first oil field that was found using science/geologic mapping, and part of the Mid-Continent oil province. By 1918, the El Dorado Oil Field was the largest single field producer in the US, and was responsible for 12.8% of national oil production and 9% of the world production. It was deemed by some as "the oil field that won World War I". In World War I, 80,000 Kansans enlisted in the military after April, 1917 when the United States declared war on Germany. They were attached mostly to the 35th, the 42nd, the 89th, and the 92nd infantry divisions.