<P> The interests in the Lucas operation at Spindletop were purchased by J.M. Guffey and his associates, creating the Guffey Petroleum Company and Gulf Refining Company of Texas . These companies later became Gulf Oil Corporation, which decades later was bought by California's Chevron . Guffey's company became the largest oil producer in the state during the boom period . Standard Oil initially chose not to become directly involved in oil production in Texas, and instead formed Security Oil Company as a refining operation utilizing Guffey - Gulf and Texas Company as suppliers . Following state lawsuits related to anti-trust statutes, Security Oil was reorganized into Magnolia Petroleum Company in 1911 . That same year, the Humble Oil Company (today Exxon Corporation) was formed by Ross Sterling and Walter William Fondren in Humble, Texas . The headquarters were moved to Houston, and the company eventually sold half of its shares to Standard Oil of New Jersey, establishing a long - term partnership that lasted for decades . The company built the Baytown Refinery, which became Texas' largest refining operation . In the post-World War II period, Humble became the largest crude oil transporter in the United States, and built pipelines connecting Baytown to Dallas - Fort Worth and West Texas to the Gulf of Mexico . </P> <P> In spite of the few major operations, the first decade of the boom was dominated by numerous small producers . As production expanded and new companies were formed, consolidation occurred . By the late 1920s, ten companies produced more than half of the oil in the state: Gulf Production Company, Humble Oil and Refining Company, Southern Crude Oil Purchasing Company (later absorbed by Amoco which was later absorbed by BP), the Texas Company, Shell Petroleum Corporation, Yount - Lee Oil Company, Magnolia Petroleum Company, J.K. Hughes Oil Company, Pure Oil Company, and Mid-Kansas Oil and Gas Company (later Marathon Oil). </P> <P> During the 1930s, a Dallas company known as the General American Finance System, struggling through the Great Depression, began to finance drilling operations in the state using oil reserves as collateral . This allowed Dallas to establish itself as the financing center for the oil industry . The Great American Finance System eventually reorganized itself as the General American Oil Company of Texas, which became an oil producer in its own right and, decades later, was purchased by Phillips Petroleum . </P> <P> At the start of the 20th century, agriculture, timber, and ranching were the leading economic engines of Texas . This was changed by the boom, which led to rapid industrialization . Though refineries were initially concentrated around the Beaumont and Houston areas, refining operations gradually grew throughout the state by the end of the 1920s . By 1940, the value of petroleum and natural gas produced in Texas exceeded the value of all agricultural products in the state . The state's GDP grew from approximately $119 million ($3.5 million in today's terms) in 1900 to approximately $29 billion ($253 million in today's terms), a more than 240-fold increase . The U.S. GDP as a whole grew by less than 24 times during the same period . </P>

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