Columbia Gas of Maryland delivers clean, affordable and efficient natural gas to approximately 33,000 customers. With headqua ... rters in Canonsburg, Pennsylvania, it is one of NiSource’s seven regulated utility companies. NiSource (NYSE: NI) is one of the largest fully-regulated utility companies in the United States, serving approximately 3.5 million natural gas customers and 500,000 electric customers through its local Columbia Gas and NIPSCO brands. read more