Twenty-two years of his engineering career was with Ford Aerospace Corporation, the defense and aerospace subsidiary of Ford Motor Company, where he rose to vice president and general manager of the division. Bob became the executive VP responsible for integration of newly acquired subsidiaries. While living in Colorado Springs, Ranking also served as vice president for the development of the Colorado Springs Symphony, as chairman of the Engineering Advisory Committee for the University of Colorado (Colorado Springs), and was appointed by Gov. Roy Romer to the Colorado Advanced Technology Institute.

In 1995, Bob and his wife Joyce moved to Aspen and founded Aspen Cybercare, LLC, an on-going technology consulting firm providing support to business and residential clientele. In 2000, Rankin founded and served as chairman of the board for the Computers for Kids Foundation, a non-profit organization recycling electronics while motivating high school students toward a career in technology.

Bob and Joyce now reside in Carbondale, Colorado, and are active members of the Colorado Republican Party. He has been appointed to serve on the House Agriculture, Livestock, and Natural Resources Committee, the House Local Government Committee, and as a member of the board of the Colorado Tourism Office Board.