Gayle Thornbrough (October 29, 1914 – November 8, 1999) was born in Hendricks County, Indiana, and grew up in Indianapolis. She joined the Indiana Historical Society in 1937 and served as its director of publications and library, an editor of historical documents, and its first executive secretary until her retirement in 1984. In addition to her work at the IHS, Thornbrough was involved in historical editing projects for the Indiana Historical Bureau from 1947 to 1966 and spent twenty months in 1967–1968 as a manuscript specialist at the Library of Congress in Washington, D.C. Thornbrough is best known for her contributions to editing historical documents. She is named as the editor of nearly twenty publications, the most notable include The Old Northwest: Pioneer Period, 1815–1840, a Pulitzer Prize winner by R. Carlyle Buley; Journals of the General Assembly of Indiana Territory, 1805–1815; Indiana Election Returns, 1816–1851; three volumes in the governors of Indiana series (James B. Ray, Noah Noble, and Samuel Bigger); and The Diary of Calvin Fletcher, among others. The Indiana Magazine of History's annual Thornbrough award and Indiana Association of Historians' annual fall lecture are named in honor of Thornbrough and her sister, Emma Lou. Early life and education Born in Hendricks County, Indiana, on October 29, 1914, Gayle was the second child of Harry C. Thornbrough, an engineer, and Bess Tyler, his wife. Gayle grew up in Indianapolis, where she graduated from Shortridge High School in 1932. She received an undergraduate degree from Butler University in 1937 and a master's degree from the University of Michigan in 1942. Thornbrough enjoyed the theater, music, and classical and modern literature. She also traveled extensively with her older sister, Emma Lou, who was an Indiana historian, author, and professor of history at Butler University. The sisters shared their childhood home throughout their lives. Career Thornbrough began her career as an editor in 1937, when she joined the Indiana Historical Society as its first full-time employee. Thornbrough became nationally recognized for her work in editing historical documents. She is listed as editor for nearly twenty publications, but also prepared more than fifty more for publication. Thornbrough was involved in historical editing projects for the Indiana Historical Bureau from 1947 to 1966 in addition to her work at the IHS. Early editing assignments for the IHS included Prehistory Research Series, "the earliest scholarly publication on Indiana archaeology," and as copyeditor for R.