Primarily papers of soil scientist Eugene W. Hilgard relating to his work on the Northern Transcontinental Survey, with the U.S. Census in 1880 and as professor, University of California College of Agriculture. Included are letters, manuscripts of his writings, subject files, lecture notes, accounts, personalia, clippings, etc.

Also in the collection: a few papers of his father, Theodor E. Hilgard, including photocopy of a letter from the Marquis de Lafayette; papers of his brother Julius E. Hilgard concerning his work with the U.S. Coast and Geodetic Survey; papers of his brother Theodore C. Hilgard, some of which relate to the magnetic survey; and papers of his daughters, Alice and Louise, primarily letters of condolence on the death of their father.