[3][4] He owned and ran a cow and calf ranch in Park, Sweet Grass, and Fergus counties in Montana.

[4][5] He served on the board of directors of the International Peace Institute, the Salzburg Global Seminar, the Rural Development Institute, the Trilateral Commission, Hubert H. Humphrey School of Public Affairs at the University of Minnesota, the Ruckelshaus Institute, the Burton K. Wheeler Center for Public Policy in Bozeman, Montana and Yale University's president's council on international activities.

[10] He was a member of the National Academy of Sciences board on agriculture and natural resources, the EastWest Institute, Care International, Mayo Clinic and the Council on Foreign Relations.

[4][5] The Whitney and Betty MacMillan Center for International and Area Studies at Yale is named for him.

[5] He was an executive fellow and teacher at the University of St. Thomas Graduate School of Business in Minnesota.