response to rumors that a conspiratorial ring of crude oil traders in New York City had cornered the market. As the decade progressed, larger producers, such as John D. Rockefeller’s Standard Oil, began to consolidate their holdings over the wells and refineries in the region, and the oil rush began to settle down. Pennsylvania oil production peaked in 1891, when the state produced 31 million barrels of oil, 58% of the nation's oil that year. But 1892 was the last year that Pennsylvania wells provided a majority of the oil produced in the US, and in 1895, Ohio surpassed Pennsylvania as an oil producer. By 1907, the decline of the Pennsylvania fields and the great discoveries made in Texas, California, and Oklahoma, left Pennsylvania with less than 10% of the nation's oil production. By 1901, the Pennsylvania oil boom was over. The formation of the Standard Oil Trust in 1882 effectively established a monopoly over the industry in Pennsylvania, and the discovery of oil in Texas, California and Wyoming shifted the nation's attention elsewhere. Pennsylvania continued to be a significant producer of petroleum for much of the 20th century, but the Oil Creek Valley had been permanently eclipsed. See also History of the petroleum industry in the United States Ohio Oil Rush Texas Oil Boom North Dakota oil boom References 19th century in Pennsylvania Oil booms History of the petroleum industry in the United States