Correspondence, memoranda, reports, and reference materials relating to Benson and topics of particular interest to him. Major subjects include parks and recreation, traffic and transportation, and the Westlake Mall Project, the Downtown Seattle Transit Project, the University District Transportation Program, the Waterfront Streetcar, gun control, land use, and solid waste disposal.

Correspondence, reports, newspaper clippings, and photographs collected by Massart while serving on City Council (1950-1967). Includes materials relating to Metro, Seattle Center, Century 21 Exposition, Pacific Science Center Foundation, and the Port of Seattle. Other subjects include transportation, city finances, housing, alcoholism, sports stadium, human rights, and urban renewal.