In the period after World War I, America entered a period of unprecedented prosperity. DeMille took advantage of this climate to embark on numerous ventures, all of which were profitable. One of his first ventures was to create Cecil B. DeMille Productions with his wife Constance as a partner. This company functioned within the various larger companies through which he released his films.
In 1922 DeMille became vice-president of the Federal Trust and savings Bank of Hollywood. In 1923 he assumed the same position at the Commercial National Bank of Los Angeles. In 1925 he became president of the Culver City Commercial and Savings Bank, which was owned by a holding company for the Bank of Italy. Founded in San Francisco by Amadeo Peter (“A.P.”) Giannini in 1904, the Bank of Italy was the first state-wide branch banking company. In 1928 Giannini merged it with his Bank of America of California. In 1930 the new entity became the Bank of America. One of DeMille’s duties was reviewing loan applications from Hollywood film companies. It was in this capacity that he approved a loan of $250,000 to his former partner Samuel Goldwyn. The loan gave Goldwyn the capital to establish the most successful independent production company in Hollywood.
In May 1919 Cecil B. DeMille founded Mercury Aviation, the first commercial airline in California. (The first scheduled-passenger airline in America had opened in Florida in 1914. The St. Petersburg-Tampa Airboat Line lasted only four months however.) Mercury was headquartered in a former barley field at the northwest corner of Wilshire Boulevard and Crescent Avenue (now Fairfax). The company lasted two years, but it achieved its purpose, which was to demonstrate that scheduled flights of both passengers and transport could sustain a company.
In 1926 Cecil B DeMille’s property holdings included commercial lots on Hollywood Boulevard, at Sunset and Cahuenga Boulevards, and on Franklin and Highland Avenues. Movie moguls Louis B. Mayer and Irving Thalberg also invested in real estate at this time, purchasing stretches of Wilshire Boulevard in West Los Angeles.
Cecil B. DeMille’s business interests included numerous oil wells across the country, most notably United Oil Wells.