1 EXHIBIT 21 SUBSIDIARIES OF THE COLUMBIA ENERGY GROUP as of December 31, 1997 State of Segment / Subsidiary Incorporation -------------------- ------------- Transmission and Storage Operations Columbia Gas Transmission Corporation Delaware Columbia Gulf Transmission Company Delaware Columbia LNG Corporation Delaware Distribution Operations Columbia Gas of Kentucky, Inc. Kentucky Columbia Gas of Maryland, Inc. Delaware Columbia Gas of Ohio, Inc. Ohio Columbia Gas of Pennsylvania, Inc. Pennsylvania Columbia Gas of Virginia, Inc. Virginia Exploration and Production Operations Columbia Natural Resources, Inc. Texas Marketing, Propane and Power Generation Columbia Atlantic Trading Corporation Delaware Columbia Energy Services Corporation Kentucky Columbia Propane Corporation Delaware Columbia Electric Corporation Delaware TriStar Capital Corporation Delaware Corporate Columbia Energy Group Service Corporation Delaware Columbia Insurance Corporation, Ltd Bermuda Columbia Network Services Corporation Delaware