How did Rockefeller use horizontal integration to build his empire?

John D. Rockefeller employed horizontal integration by acquiring and consolidating competing oil companies to eliminate competition and gain control over the oil industry. This strategy allowed him to increase production efficiency and reduce costs, ultimately leading to lower prices for consumers. By dominating the market, he established the Standard Oil Company as a powerful entity, enabling him to dictate terms within the industry and secure substantial profits. Through this method, Rockefeller effectively created a monopoly that transformed the oil industry in the United States.