HALIFAX, NOVA SCOTIA AND HOUSTON, TEXAS, May 4, 2001—El Paso Corporation (NYSE:EPG) and Marathon Oil Company (NYSE:MRO), a unit of USX Corporation, announced today that they have agreed to conduct a feasibility study for a major new pipeline system to transport natural gas supplies between Nova Scotia, Canada and the Northeastern regions of the United States.

The Geological Survey of Canada suggests there could be more than 18 trillion cubic feet of natural gas reserves from known and potential discoveries located offshore Nova Scotia, while other studies have suggested even higher estimates. This natural gas would be well situated geographically to provide energy supplies for nearby growing markets. Tennessee and Marathon have completed a preliminary feasibility analysis to examine technical and environmental issues. Preliminary findings were favorable and the two companies have agreed to proceed with further study.

"We have assessed that there is real value to be created by giving all participants along the value chain a new option for natural gas deliveries," said E. J. Holm, chief executive officer of the Eastern Pipeline Group for El Paso Corporation. "This pipeline study is in response to the continued increase in demand for natural gas in Canada and the Northeastern United States. We are pleased to be aligned with Marathon and are also considering joining with other U.S. and Canadian parties who can bring value to the project."

Clarence P. Cazalot Jr., president of Marathon Oil Company, stated "A new pipeline to safely and efficiently transport gas to market would add considerable value to any new gas reserves discovered offshore Nova Scotia. The area has significant potential and we will be working to fully understand and address what is important to key stakeholders and local communities in Nova Scotia, Canada, and the Northeastern United States. This would include assessing potential economic and industrial opportunities associated with a landfall in Nova Scotia."

Marathon Oil Company, part of the USX?Marathon Group (NYSE: MRO) and a unit of USX Corporation, is a large fully integrated oil firm engaged in the worldwide exploration and production of crude oil and natural gas. Through Marathon Ashland Petroleum LLC, the Company also refines, markets and transports petroleum products in the United States. Visit the company's Web site at www.marathon.com or www.usx.com.

El Paso Corporation, the largest and most broadly based natural gas company in the world, spans the energy value chain from wellhead to electron. With an enterprise value in excess of $50 billion, El Paso is a leader in every phase of the natural gas industry. The company owns and operates a significant portion of the North American natural gas delivery grid, operates the fastest growing, most sophisticated energy merchant group, and is the nation's third largest natural gas producer. El Paso, a leader in risk management techniques, is focused on maximizing shareholder value, transforming existing markets, and speeding the development of new markets. Visit El Paso at www.elpaso.com.

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This release includes forward-looking statements and projections, made in reliance on the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Both companies have made every reasonable effort to ensure that the information and assumptions on which these statements and projections are based are current, reasonable, and complete. However, a variety of factors could cause actual results to differ materially from the projections, anticipated results or other expectations expressed in this release. While the companies make these statements and projections in good faith, neither the companies nor their managements can guarantee that the anticipated future results will be achieved. Reference should be made to the companies' (and their affiliates') Securities and Exchange Commission filings for additional important factors that may affect actual results.