About Transource® Transource® is a partnership between American Electric Power (AEP) and Great Plains Energy (GPE) focused on the development of, and investment in, competitive electric transmission projects across the United States. In all, AEP and GPE own and operate nearly 45,000 miles of transmission lines and have more than 100 years of expertise in the planning, design, engineering, construction and operation of transmission systems. AEP owns 86.5 percent of Transource. GPE owns 13.5. Transource is a member of three regional transmission organizations — PJM Interconnection, the Midwest Independent System Operator (MISO) and the Southwest Power Pool (SPP) — which together serve all or part of 28 U.S. states, the District of Columbia and the province of Manitoba in Canada. Headquartered in Columbus, Ohio, Transource also has offices in Kansas City, Missouri ; Tulsa, Oklahoma ; and Dallas, Texas.