Chevron Corporation is an American multinational energy corporation predominantly specializing in oil and gas. The second-largest direct descendant of Standard Oil, and originally known as the Standard Oil Company of California, it is active in more than 180 countries. Founded originally in Southern California during the 1870s, after the breakup of Standard Oil, Socal grew quickly on its own by continuing to acquire companies and partnering with others both inside and outside of California, eventually becoming one of the Big Oil companies that dominated the global petroleum industry from the mid-1940s to the 1970s. In 1985, Socal merged with the Pittsburgh-based Gulf Oil and rebranded as Chevron; the newly merged company later merged with Texaco in 2001. Chevron is one of the largest companies in the world and the second-largest oil company based in the United States by revenue, only behind fellow Standard Oil descendant ExxonMobil. Within oil and gas, Chevron is vertically integrated and is involved in hydrocarbon exploration, production, refining, marketing and transport, chemicals manufacturing and sales, and power generation.