Public Service Company of Oklahoma (PSO) has served Oklahoma's electric energy needs since the company's incorporation in May 29, 1913. PSO today serves approximately 562,000 customers in 232 cities and towns across 30,000 square miles of eastern and southwestern Oklahoma. PSO is headquartered in Tulsa, with regulatory and external affairs offices in Oklahoma City. The company's distribution operations are organized into three districts: Tulsa, Lawton, and McAlester. PSO is part of the American Electric Power system (AEP), which is based in Columbus, Ohio.