Which trust controlled 90 percent of the oil refinery business in the United States?

The Standard Oil Trust is recognized for controlling approximately 90 percent of the oil refinery business in the United States during its peak. Founded by John D. Rockefeller in 1870, the Standard Oil Company grew to dominate the oil industry through aggressive business practices such as secret deals with railroads for favorable shipping rates, strategic expansions, and the consolidation of smaller oil companies into a single trust. This monopolization enabled Standard Oil to achieve unprecedented efficiencies and cost reductions, making it the preeminent force in the industry. The sheer scale and influence of Standard Oil during this time exemplify the trends of industrial consolidation and the rise of monopolies in the late 19th and early 20th centuries, leading to significant regulatory responses such as the Sherman Antitrust Act of 1890. Understanding the ramifications of Standard Oil's dominance can illuminate key themes in American economic history, including the tension between capitalism and regulation.