Part I (1937-1968, bulk 1950-1968) consists of general correspondence, subject files, and personal papers of the brotherhood's founder, A. Philip Randolph, documenting the growth and functions of the union chiefly after 1940. Includes agreements with railroad lines; exchanges with the American Federation of Labor, Congress of Industrial Organizations, local unions, and labor organizations representing dining car employees, locomotive firemen, and railway clerks; and files relating to conventions, financial matters, and the organization's women's auxiliary. Correspondents include Randolph's principal aides A.R. Blanchette, C.L. Dellums, Benjamin F. McLaurin, T.D. McNeal, Bennie Smith, and Milton P. Webster; labor leaders Dave Beck, David Dubinsky, William Green, George Meany, Philip Murray, Mike Quill, Woodruff Randolph, and Roy, Victor, and Walter Reuther; and political and civil rights leaders Julian Bond, James Farmer, Martin Luther King, Jr., Floyd B. McKissick, Thurgood Marshall, Adam Clayton Powell, Joseph L. Rauh, Bayard Rustin, Arthur B. Spingarn, Chuck Stone, Walter Francis White, Roy Wilkins, and Whitney Young. Also includes letters from African labor organizer Tom Mboya concerning his activities in Kenya.

Part II (1920-1968, bulk 1950-1968) consists of correspondence and subject files of brotherhood officials Benjamin F. McLaurin (international field organizer), A. Philip Randolph (founder and president), and Ashley L. Totten (secretary-treasurer); and other subject files, financial records, and miscellaneous records. Includes material relating to the Brotherhood of Locomotive Firemen and Enginemen, National Advisory Committee on Farm Labor, and National Sharecroppers' Fund; organizing activity of the brotherhood in Canada; and McLaurin's campaign for New York City Council in 1945.