Originally founded in 1905 during the Gold Rush of California, PG&E became the company it is today when San Francisco Gas and Electric Company and the California Gas and Electric Corporation merged. Combined, these companies benefited through a larger market base to increase financing and the reinforcement of steam-operated generating plants with an electric system. Over the years, PG&E continued its expansion into railway operations, hydroelectric storage and generation, natural gas sales and pipelines, as well as nuclear energy. In 1998, the regulation of California public utilities changed under the regulation of the California Public Utilities Commission, a regulatory agency that oversees privately-owned public utilities in the state. This agency set the rates that PG&E could charge customers and required the utility to provide as much power as customers demand.
Since the early 2000s, the company has aggressively promoted its environmental image and increased its use of renewable energy sources. PG&E has maintained its extensive hydroelectric generation facilities and is one of the largest private owners of hydroelectric facilities in the United States. In 2010, the company also began to install smart meters and is one of the largest installers of smart meters in the United States.