Robert Louis Gilmore was born on September 8, 1913, in Fremont County, Iowa. He graduated from Creighton University with a B.A. in Classics in 1935 and earned his M.A. in History in 1939. He began work on his doctorate in Latin American history at the University of California-Berkeley and received a fellowship to study in Colombia in 1941.

While in Colombia, Gilmore was ordered into active duty in the Air Corps and sent to Photo Intelligence School. His squadron was responsible for obtaining data to make maps from aerial photographs; Gilmore was responsible for studying the interior of much of Brazil and Guayana. He returned to civilian life in 1946 and completed his doctorate in 1949.

Gilmore guest lectured at University of Guadalajara, then accepted appointments at Vanderbilt University, the Office of Intelligence and Research at the State Department, and Ohio University, where he helped revise the history department and implement a Ph.D. program. He joined the KU faculty as a professor in 1968, and served as Director of Graduate Studies and Associate Chairman of the Department of History from 1970-1973.

Gilmore served as the Chairman of the Gran Colombian Section of the Conference of Latin American Historians, as well as President and Vice-President of the Mid-West Association for Latin American Studies. He was also a member of Alpha Sigma Nu. Gilmore retired in 1978 to devote his time to a small vineyard outside of Lawrence he had begun in 1973. He died in 2002.