A historian of the modern United States, he is the author of Oil, War, and American Security (1980) and a coauthor of Experience History: Interpreting America's Past (8th edition, 2014) as well as high school and middle school textbooks. A series coeditor of Oxford New Narratives in American History, he is also a coeditor of The Manhattan Project: A Documentary Introduction to the Atomic Age (1991) and is currently working on a book on the bombing of Nagasaki. He has received numerous teaching awards, including the 2012 Regents' Outstanding Teaching Award, the first system-wide teaching award ever offered by the University of Texas Regents.