Rankin grew up in Montana and received an MFA at the University of Montana. He did postgraduate work at Montana State University, studying primarily printmaking, painting and sculpture. His career as an art teacher and professor began in Alaska in 1964, with one of his notable students being artist Wes Mills. Since 1985, he has devoted his life to painting full-time. He began exhibiting at the Henry Art Gallery at the University of Washington in the late 1950s and is included in the permanent collections of Viterbo College in LaCrosse, Wisconsin; Yellowstone Art Museum in Billings, Montana; the Pritchard Gallery in Moscow, Idaho; and the Missoula Art Museum in Missoula, Montana.
Rankin's eclecticism marries a selection of energized forms and colors to create an image of the West at once regional and universal, which Rankin describes as a "connective thread tying me to the West - or to the world." Highly conceptual, Rankin's work is related to music-metaphorically rhythmic, exploring the pause which exists between colors or forms and relies on repeated themes and images.
In the 1980s, Rankin was featured in a touring exhibition across the Szechuan Province in China and has been the recipient of Museum and Art Gallery Directors Association Traveling Arts Grants in 1995 and 2000, the latter of which hosted a touring retrospective of his work.