Kreps was the Commerce secretary from 1977 to 1979 during the presidency of Jimmy Carter. She directed the Commerce Department toward a more active role in promoting international trade and initiated a historic trade agreement between the United States and China in 1979.
Kreps joined the faculty at Duke in 1962. Besides teaching economics, she also served as dean of the Women's College and assistant provost, from 1969 to 1972, and was named vice president of the university in 1973.
Political advisor Anne Wexler, who was serving on Carter's transition team after his victory in the 1976 presidential election, recommended Kreps for a post in the new administration, and she became the first economist to be named secretary of Commerce.
"It was an unusual appointment, since most Commerce secretaries at that time were businessmen who just wanted that line on their resume," said Craufurd Goodwin, a longtime Duke colleague. "She wasn't in the inner circle in Washington, but she was very self-confident and didn't take any nonsense from anybody."
Kreps resigned her post and returned to Durham after her husband, Clifton H. Kreps Jr., a business professor at the University of North Carolina, attempted suicide.
Born Blair Juanita Morris on Jan. 11, 1921, in Lynch, Ky., she received a bachelor's degree from Berea College in Kentucky in 1942 and her master's degree (1944) and doctorate (1948) in economics from Duke.
She served on the faculties at Denison University, Hofstra University and Queens College in New York before joining the economics department at Duke.
Survivors include a daughter, a son and four grandchildren. Her husband died in 2000.