Ray Allen Billington (1903-81) trained several generations of western historians and published numerous books on American frontier history, including America's Frontier Heritage (UNM Press).

Martin Ridge is a senior research associate in the Henry E. Huntington Library. He has taught at San Diego State University, Indiana University, and the California Institute of Technology. He is the former editor of the Journal of American History and the past president of the Pacific Coast Branch of the American Historical Association and Western History Association. He is the author of numerous scholarly and review articles dealing with the American West. He is the coeditor of Histories of the American Frontier.