These records cover the years 1966-1974 and are arranged alphabetically within six series: Campaign; Correspondence; Departments; Legislation; Organizations; and Miscellaneous.

The collection contains material on many subjects, including cities, counties, and colleges of Iowa's sixth congressional district. Series II, Correspondence, is arranged alphabetically within a general chronological structure. Special topics of interest include agriculture, conservation, education, energy, postal services, railroads, Sioux City Steak Dinners, taxes, U.S. Army Corps of Engineers, and the Vietnamese Conflict. While serving on the Judiciary Committee, Mr. Mayne was involved with the Watergate hearings, the impeachment proceedings against Richard M. Nixon, and the confirmation hearings of Nelson A. Rockefeller as Vice-President. After leaving office, Mayne resumed his law practice in Sioux City, Iowa, with the firm of Mayne and Berenstein.