Robley Evans Winfrey was born on September 7, 1899, in Runnels, Iowa, to Thomas Henry and Kathryn (Gibbs) Winfrey. He received his B.S. (1922) and M.S. (1926) in civil engineering from Iowa State College (University). He also earned the Professional Degree (1942) in civil engineering.

Winfrey joined the staff at Iowa State as Research Engineer and Editor (1922-1935) of the Engineering Experiment Station Bulletin. He was named Associate Professor (1939-1942) of civil engineering and then promoted to Professor (1946-1952). He left Iowa State for a position in the U.S. Bureau of Public Roads where he served as Chief of Personnel and Training (1952-1960) and Chief of the Economic Research Division (1960-1969). He then went into private practice as a Consulting Civil Engineer in Washington, D.C.

During his time at Iowa State, Winfrey twice took leave to further serve his country. He was granted leave for special duties with the U.S. Bureau of Public Roads from 1935-1939. In World War II, he served as an intelligence officer and during the war was stationed in London, Washington, D.C., and Pearl Harbor. He was discharged with the rank of Colonel in 1946.

Winfrey was a member of many professional societies and the author of several major publications. He was elected a Fellow of the American Society of Civil Engineers and held membership in the Institute of Traffic Engineers and the American Society for Engineering Education. As an author and researcher, perhaps his most famous work was Iowa Engineering Experiment Station Bulletin 125, "Statistical Analyses of Industrial Property Retirements" (1935), which introduced the Iowa-type survivor curves for use in calculating property depreciation. He authored several other bulletins including Bulletin 155, "Depreciation of Group Properties," which also has been heavily used by the insurance industry. Winfrey also authored or co-authored several textbooks including Engineering Valuation and Depreciation (call no. TA178 M359e2) and Economic Analysis for Highways (call no. TE145 W57).

Robley Winfrey married Verne Cooper on September 2, 1923. Together they had two sons, Robley II and James. Winfrey died on April 13, 1993, in Ames, Iowa, and was buried in the Iowa State University Cemetery.

The collection (1933-1993, undated) contains biographical information and correspondence of Robley Winfrey along with copies of two of his most influential works on industrial property depreciation and retirements. The reports, originally published by the Iowa Engineering Experiment Station at Iowa State College (later dubbed the Engineering Research Institute, Iowa State University) introduced the Iowa-type survivor curves used for appraising property depreciation. This collection contains the revised edition of Bulletin 125, "Statistical Analyses of Industrial Property Retirements," and a reprint of Bulletin 155, "Depreciation of Group Properties." Both bulletins are loose-leaf and suitable for making copies. The collection also contains copies of the Iowa-type survivor curves found in Bulletin 125. These copies have been reproduced in a larger format than can be found in the original report.

Original copies of the Iowa Engineering Experiment Station Bulletins are cataloged in the University Archives (call no. TA1 Io8b).

The collection is organized alphabetically.