After retiring from UCLA in 1966, Powell moved to Tucson, Arizona in 1971, where—as Professor in Residence for nearly two decades—he was instrumental in the growth of the University of Arizona Graduate School of Library Science, now known as the University of Arizona School of Information Resources and Library Science. The University of Arizona Libraries special collections holds Powell's papers documenting his time in Tucson, and the Fay and Lawrence Clark Powell Endowment for Southwest Research continues to support Powell's interest in the geography of the southwest United States.