1950-1952 Pforzheimer Papers: Westchester County Association Records (Series 161)
1950, 1973-1981 (bulk 1974-1976) Bicentennial Commission of Westchester County Records (Series 48)
1951-1978 Parks Department, Programs and Services Division Reports (Series 126)
1951, 1966-1989 (bulk mid-1970s-early 1980s) Parks Department Director of Management Planning and Property Records (Series 383)
1952-1977 Court Administration Reports (Series 101)
1953-1991 Naturalizations -- Transfers (Series 290)
1955-1956 Community Mental Health Board – Miscellaneous Records (Series 369)
April 1955-September 1961 “Westchester County News” [Press Releases] (Series 365)
1955-1970, 1974-1983 Veterans Peddler Licenses (Series 324)
1956-1973 Court Administration Financial Records (Series 71)
1956-1982 County Clerk Financial Records (Series 54)
1957-1961 Charter and Administrative Code Revision Committee Records, 1957-1961
1957-1977 Court Administration Personnel Records (Series 150)
1957-1980 Land Records Division Miscellaneous Records (Series 57)
1957-1997 (bulk 1984-1988) Westchester 2000 -- Sal Prezioso Collection (Series 281)
1958-1973 Michaelian, Edwin G. Collection: Speeches and Proclamations (Series 394)
1958-1974 Edwin G. Michaelian Collection: County Executive Records, Invitations and Thank-Yous (Series 100)
1958-1984 (bulk 1958-1973) Edwin G. Michaelian Collection: County Executive Records (Series 26)
1958, 1965-1982 Motor Vehicles Division Miscellaneous Records (Series 61)
1959-1960 Recreation Commission Minutes (Series 92)
1959-1975 (bulk 1962-1972) Youth Services Division Records, Office of the County Executive (Series 376)
1959-1977 Court Administration Facilities Records (Series 151)
1960-1967 Interstate 684 Records (Series 23)
1960-1973 Environmental Health Services Annual Reports (Series 199)
1960-1984 Board of Supervisors / Board of Legislators – Local Laws, 1960-1984
1960-1990 (bulk 1973-1990) Department of Consumer Affairs, Weights and Measures Publicity Clippings (Series 274)
1961-1967 Department of Social Services: Social Welfare Department Monthly Report Bulletins (Series 178)
1961-1972 Environmental Health Services Monthly Reports (Series 206)
1962, 1964 Parks Department Statistical Ledgers (Series 353)
1962-1978 Parks, Recreation and Conservation Board Minutes (Series 93)
1962-1978 (gaps) Parks, Recreation and Conservation Board Agenda (Series 146)
1962-1981 Land Records Division Reports (Series 58)
1966-1975 (bulk 1968-1974) Public Works Engineering Office Correspondence Files (Series 362)
1967-1977 Board of Elections Hotel Register (Series 3)
1967-2005 (bulk 1980s-1990s) Parks Department Marketing/Public Relations Subject Files (Series 328)
1968-1974 County Office Building Plans - Access Restricted (Series 256)
1968-1981 Records and Archives Division Miscellaneous Records (Series 62)
1969-1981 Alfred B. Del Bello Subject Files (Series 304)
1970-1975, 1977-1992 Community Mental Health Board / Community Services Board Minutes and Meeting Packets (Series 361)
1970-2000 Board of Legislators Board Meeting Packets (Series 308)
1970-2007 Board of Legislators Proceedings (Series 147)
1971-1998 Westchester 2000 (Series 275)
c.1973-2007 (gaps) Parks Department Slide Collection (Series 323)
1974-1984 Edwin G. Michaelian Collection: Post-County Executive Papers (Series 27)