On May 19, The Williams Cos. Inc. said Stephen W. Bergstrom was elected as chairman of the board, effective immediately, replacing Kathleen B. Cooper. Bergstrom joined Williams’ board in August 2016.

Cooper will become chair of the board’s nominating and governance committee, and has served on the board since 2006.

Bergstrom is a director on the board of American Midstream Partners, and served as president and CEO of American Midstream’s general partner and as executive chairman of the general partner’s board of directors from May 2013 to December 2015.

He was an exclusive consultant to ArcLight from October 2003 to December 2015. Prior to that, he worked from 1986 to 2002 for Natural Gas Clearinghouse, which became Dynegy Inc. Ultimately, he was Dynegy’s president and COO, the press release said.

Bergstrom earned a bachelor’s degree from Iowa State University.

The board of Tulsa, Okla.-based Williams has 11 members, 10 of whom are independent.

Cooper is currently president of Cooper Strategies International LLC. From 2001 to 2005, she was under-secretary for economic affairs at the U.S. Department of Commerce. Prior to that, she was chief economist for ExxonMobil Corp. (NYSE: XOM).

She also serves as a director of Deutsche Bank Trust Corp. and Deutsche Bank Trust Co. of the Americas, subsidiaries of Deutsche Bank AG, the press release said. She was a founding director of Texas Security Bank from 2008 to 2010.

Earlier in her career, she was executive vice president and chief economist of Security Pacific National Bank and chief economist of the United Banks of Colorado.

Cooper has a doctorate from the University of Colorado.