The agency's reach expanded as it took over responsibility for regulating oil pipelines (in 1917), oil and gas production (1919), natural gas delivery systems (1920), bus lines (1927), and trucking (1929). It grew from 12 employees in 1916 to 69 in 1930 and 566 in 1939. It does not have jurisdiction over investor owned electric utility companies; that falls under the jurisdiction of the Public Utility Commission of Texas.[9][10]