Oscar Osburn Winther was born in Weeping Water, Nebraska on December 22, 1903. After graduating from Eugene High School in Eugene, Oregon, he attended the University of Oregon, earning a Bachelor's degree in history in 1925. Winther continued his education in history, earning a Master's degree from Harvard in 1928 and a Ph.D. from Stanford University in 1934. After completing his Ph.D., he remained at Stanford as an Instructor in the History Department.
Winther joined the faculty of Indiana University in 1937. Initially appointed an Instructor in the Department of History, he was made an Assistant Professor in 1943. Other promotions soon followed, with Winther being named Associate Professor in 1947 and Professor in 1950. He also took an active role in administrative matters, serving on numerous committees and as Assistant and Associate Dean of the Graduate School from 1949 to 1958.
An enthusiastic and very productive scholar, Winther published extensively in the field of Western U.S. history. He authored some 13 books, dozens of journal articles, and more than 125 book reviews. Believing strongly that historians should attempt to reach the general public as well as academics, he wrote a number of brochures, encyclopedia articles, and grade-school textbooks. His book Via Western Express and Stagecoach, published in 1945, was also intended to be accessible to a non-scholarly audience.
This attention to those outside academia in no way detracted from his reputation as a scholar. Winther was well-known and respected as an expert in his field, winning Fulbright Fellowships in 1952 and 1965. He was awarded a Guggenheim fellowship in 1959, as well as research grants from the Huntington Library, the Library of Congress, Chicago's Newberry Library, and several Indiana University grants. Additionally, he was named a Fellow of Britain's Royal Historical Society and the Society of American Historians.
His expertise in Western history and the Pacific Northwest also resulted in numerous invitations from other universities. Offered several faculty positions during his career, he turned them down in favor of remaining at Indiana. He did, however, serve as a visiting professor at such institutions as Johns Hopkins, the University of Oregon, Brigham Young, and the University of Washington.
Indiana University did not take his reputation for granted. He was recognized for his abilities as a scholar and selected to serve as editor of the Mississippi Valley Historical Review. Following its move to Indiana in 1963, it was Winther who oversaw the publication's transformation into the Journal of American History. He continued as editor of the journal until 1966. In further recognition of his achievements, Winther was named University Professor of History in 1965.
Though he remained an active scholar and teacher, Winther had been facing serious problems with his health for some time. By late 1969 he was too sick to continue the pressing workload which he had maintained throughout his career. After a long battle with cancer, Oscar Winther died on May 22, 1970 at the age of 66.