Plank graduated from Yale University in 1944 with a Bachelor of Arts degree. He served with the U.S. Army Air Corps as a bomber pilot in the South Pacific theater of operations during World War II.
Following his military service, Plank returned to his hometown of Minneapolis and, with two partners, formed an accounting, tax and small business advisory service. Through this enterprise, he became familiar with the types of investments then being offered in oil and gas exploration and production. Recognizing that investors' interests in this field could be better served through a different concept, Plank formed Apache Corporation in 1954.
Apache offered its first oil and gas investment program in 1956. Under Plank's leadership, Apache has evolved from a company which raised investor funds for drilling into an international oil and gas exploration and production corporation which funds its drilling with internally generated cash flow.
Plank retired after five decades of building the company into one of the nation's largest and most highly respected oil and gas independents.
Plank has consistently been active in civic, educational and business affairs. He chairs the Ucross Foundation in Wyoming. He served as chairman of the Wyoming Futures Project and co-chairman of Minnesota Wellspring, was a founding member of Freedom Lift; Friends of Mesa Verde, Springboard, and Close Fund for Teaching Nurses. Plank has been a trustee of Carleton College where Apache established the Raymond Plank Chair in Incentive Economics, and is past chairman of the University of Minnesota Foundation.