Southwest Power Pool, Inc. (SPP) was founded in 1941 by a coalition of regional power companies interested in keeping an Arkansas aluminum factory supplied with power to meet critical defense needs. Since 2004, SPP has been recognized by the FERC as a Regional Transmission Organization or RTO. Today, SPP organizes and operates parts of the electric power grid in nine states: Arkansas, Kansas, Louisiana, Mississippi, Missouri, Nebraska, New Mexico, Oklahoma, and Texas.
On September 11, 2014, pursuant to section 205 of the Federal Power Act (FPA), SPP submitted to the FERC proposed revisions to its governing documents to facilitate the decision of three major transmission owners of the so-called Integrated System in the Upper Great Plains to join SPP. The three proposed member-owners are:
- Western Area Power Administration – Upper Great Plains Region: one of four regions of the United States Department of Energy's Western Area Power Administration. Western is a federal power marketing agency that markets federal power and owns and operates transmission facilities through 15 western and central states, encompassing a geographic area of 1.3 million square miles. Western ’s primary mission is to market federal power and transmission resources constructed with Congressional authorization. The federal generation marketed by Western is generated by power plants that were constructed by federal generating agencies, principally the Department of the Interior’s Bureau of Reclamation and the U.S. Army Corps of Engineers. In the Upper Great Plains Region , or Western - UGP, Western owns an extensive system of high - voltage transmission facilities and markets federally generated hydroelectric power in the Pick - Sloan Missouri - Basin Program - Eastern Division of Western.
- Basin Electric Power Cooperative: serves 2.8 million customers in territories covering approximately 540,000 square miles using nearly 2,100 miles of transmission lines and 70 switch yards
- Heartland Consumers Power District: a public corporation and political subdivision of the State of South Dakota. It provides wholesale power to 28 municipalities in eastern South Dakota, southwest Minnesota, and northwest Iowa, to six South Dakota state agencies, and to one electric cooperative in South Dakota.
By order dated November 10, 2014, the FERC accepted SPP's proposal. Together, these new SPP members provide the backbone of the bulk electric transmission system across seven states in the Upper Great Plains region consisting of approximately 9,500 miles of transmission lines rated 115 kV through 345 kV. The FERC order directed SPP to take certain interim steps, and SPP has announced plans to integrate the three new utilities by October 2015.