Barr's primary research focus on the history of the Civil War, Reconstruction, the American South, and African Americans. His publications include Polignac's Texas Brigade, a study of Prince Polignac and the Texan soldiers who fought in 1864 in the Battle of Mansfield in northwestern Louisiana. A monument to the Texan soldiers was dedicated at the site on the centennial of the Civil War battle in April 1964. His first major monograph came out in 1971, Reconstruction to Reform: Texas Politics, 1876-1906. Next came the first edition of Black Texans: A History of African-Americans in Texas, 1528-1971 that he later updated with a new preface, new chapter on 1970-1995, and new index. Another Barr work is The African Texans, which describes the experience of free blacks and slaves prior to the Civil War and concludes with late 20th-century political developments. In 1981 Barr and Robert A. Calvert, late historian at Texas A&M University, co-edited Black Leaders: Texans for Their Times. In 2000 Barr wrote the introduction to Black Cowboys of Texas ed. Sara R. Massey. In addition to his previously mentioned research interests, Barr has also done extensive research in military history. In 1990, he published a short study entitled Texans in Revolt: The Battle for San Antonio, 1835 that remains the primary study of the capture of San Antonio by Texans and Tejanos during the Texas Revolution prior to the fall of the Alamo in the spring of 1836. He has published forty-eight articles in history journals including Civil War History, Military Affairs, the Journal of African American History, the Southwestern Historical Quarterly, the Social Science Quarterly, and Military History of the West. He has secured multiple awards for his teaching, research, and leadership at Texas Tech. In 1992-1993 academic year, he served as the president of the Texas State Historical Association. In 2001, Barr received the Outstanding Researcher Award from the Texas Tech College of Arts and Sciences. In 2005, he obtained the Faculty Distinguished Leadership Award from the Texas Tech Association of Parents. In 2011, Barr was inducted into the Texas Institute of Letters. Thirty-three doctoral students at Texas Tech completed their studies under Barr, and eleven of their dissertations were revised and published as books. He has been a consultant for the National Park Service, National Endowment for the Humanities, Humanities Texas, the U.S. Department of Justice, Smithsonian Productions, and for the 2006 public television documentary Texas Ranch House, a reality show in which modern Americans attempted to live as they would have in the year 1867. Among Barr's colleagues at Texas Tech were Paul H. Carlson, Allan J. Kuethe, Dan Flores, and Ernest Wallace. In 2012, Barr wrote the foreword to the book Where the West Begins: Debating Texas Identity, by Glen Sample Ely of Fort Worth. The book is a new interpretation of the areas west of the 100th meridian which encompass West Texas. Barr and his wife, the former Nancy Dement, reside in Lubbock. Their daughters are Juliana Barr and Alicia Barr.
