In subsequent years, the FPC also regulated interstate natural gas and electric utilities.
In June 1939, President Roosevelt appointed Leland Olds to the FPC, and Olds served as chairman of the commission from January, 1940 until 1949. Under his leadership the Federal Power Commission successfully pressured electric utilities to extend power into neglected rural areas and to lower electricity rates in order to increase use.
His insistence on enforcing the Natural Gas Act of 1938 raised the ire of the Texas Oil industry and led to the end of his career at the Federal Power Commission. Robert Caro's book Master of the Senate describes how Lyndon B. Johnson defeated Leland's re-appointment by orchestrating a McCarthyism style smear campaign. This involved utilizing the staff of the House Un-American Activities Committee to dig up old writings which were then taken out of context to falsely paint Leland as a communist. The subcommittee in charge of reappointment was stacked against Leland and coached by Johnson.
Another prominent FPC Commissioner was James G. Watt, who conducted prayer meetings prior to Commission sessions.
On October 1, 1977, the FPC was replaced by the Federal Energy Regulatory Commission.