The United States acquired California in 1848, after winning the Mexican-American War. The community of Newhall is named after Henry Newhall, an American businessman who made his fortune during the California Gold Rush. He founded the H.M. Newhall & Company, a successful auction house in San Francisco. Newhall's next business interest was railroads. He invested in rail companies that would connect San Francisco to other cities and became president of the San Francisco and San Jose Railroad. In 1870, he and his partners sold the company to Southern Pacific Railroad, and he served on Southern Pacific's board of directors.