Chalffy Atmos Energy Corporation (NYSE:ATO) is one of the largest pure-play natural gas utilities in the United States, boasting operations in eight states in the central and southern parts of the nation:   Atmos Energy The company currently serves approximately 3.3 million customers throughout these states, which is less than we might expect. After all, Texas alone has approximately 30.9 million inhabitants. However, natural gas utilities are a bit different from electric utilities as they do not neces ...