1900-1933 Assumed Business Names Index (Series 46)
1900-1977 (bulk 1922-1930) V. Everit Macy Papers (Series 187)
1901-1917 Good Roads Records (Series 333)
1901-present Westchester County Government Publications (Series 200)
1903-1973 Jail Blotter Books (Series 310)
1903, 1981, 1995 Department of Correction Historical Records Collection (Series 309)
1904-1943 Osteopaths Register and Affidavits (Series 40)
1905, 1915, 1925 Census Rolls (New York State) (Series 19)
1905-1951 Pforzheimer Papers: Purchase Property Owners Association (Series 158)
1906-1980 Declarations of Intention (Series 33)
c.1906-1933 Bronx Parkway Commission Land Acquisitions (Series 109)
1906-1966 Mortgage Tax Records (Series 121)
1907-1916, 1939 Bronx Valley Sewer Records (Series 166)
1907-1915 Naturalizations -- Court Calendars (Series 291)
1907-1925 (gaps) Bronx Parkway Commission Annual Reports (Series 95)
1907-1925 Bronx Parkway Commission Minutes (Series 118)
1907-1922, 1935-1981 County Elections and Appointments Records (Series 152)
1908-1914, 1917-1935 Marriage License Affidavits, Licenses, and Certificates (Series 169)
1908-1918 Marriage Certificates and Record with Abstract of Affidavit (Series 184)
1908-1935 (gaps) Marriage Certificates Index (Series 183)
1909-1950 Optometrists Register (Series 351)
c.1910s-c.1930s Park and Parkway Property Acquisition Deeds (Series 350)
ca. 1910-1940 Parks Department Miscellaneous Photograph Collection (Series 384)
1910-1960 Witness Depositions In Support of Petitions for Natualizations (Series 288)
1911-1927, 1935-1950 Board of Elections Minutes (Series 141)
1912-1913 Stallion Pedigree Register (Series 246)
1912-1922 Insurance Agents Certificates Index (Series 73)
c.1912-1932 Photographic Indexes (Series 264)
1912-1949 Farm Names Register (Series 1)
1912-1956 Board of Elections Bills and Expenses (Series 49)
c.1912-1970 Park Commission Indexes to Park and Parkway Deeds (Series 382)
1913-1930 V. Everit Macy Scrapbooks (Series 188)
1914-1937 (bulk 1934-1936) Elizabeth Shepard Lough Papers: Commission on Government (Series 303)
1914-1916, 1920-1921, 1923-1961 Department of Social Services: County Home Division Reports (Series 175)
1914-1938, 1941-1943, 1946-1974 Indexes to Jail Blotter Books (Series 311)
c.1914-1985 Park Commission Land Record Cards (Series 380)
1914-1998 (1967-1991 bulk) Planning Commissioner Peter Q. Eschweiler Collection (Series 368)
March 1915-November 1916 Westchester County Building Commission – Courthouse Construction Records (Series 389)
1915-1920 Bronx River Parkway Plans (Series 255)
1915-1967 Law Department Historical Records (Series 325)
1915, 1948-1968 Courthouse Development Committee Records (Series 24)
1915-1972 Department of Social Services: Director of Public Welfare Reports (Series 172)
1916-1924, 1928-1930 Bronx Parkway Commission, Appraisal Commissioners, Minutes (Series 103)
1916-1924 Bronx Parkway Commission, Appraisal Commissioners, Appeals (Series 104)
1917, 1939, 1949, 1953-1974 Parks Department Consultant Reports (Series 107)
c.1917-2011 Elijah Miller House / Washington’s Headquarters Museum Records (Series 372)
1918 World War I Alien Registration Forms (Series 373)
1918, 1932, 1983 Miscellaneous Historic Records Collection (Series 20)
1918, 1922-1936, 1970-1971, 1976-1989, 1991, 1997-2008 Parks Department Clippings (Series 98)
c.1919-1941 Lloyd B. Cox Papers (Series 133)
1919-1951 Architects Register (Series 4)
1919-1965 Parks Department State and County Road Records (Series 114)
c.1920s-1932 Park Commission Index to Condemnation Proceedings (Series 385)
c.1920s-1940s Park Commission Land Acquisition Name Index Cards (Series 381)
c.1920s-1970s (bulk 1920s-1930s) DPW Parks and Parkways Acquisition Maps (Series 313)
c.1920 Peekskill Scrapbook (Series 186)
1920-1952 Pforzheimer Papers: Harrison-Purchase Citizen Committees (Series 159)
c.1920-1985 Veterans' Discharges (Series 87)
1921-1926 Marriage Licenses Issued (Series 185)
1921-1955 Pforzheimer Papers: Miscellaneous Publications (Series 162)
1921-1956 (bulk 1934-1937) Pforzheimer Papers: Commission on Government (Series 164)
1922-1941 (bulk 1922-1935) Parks Department State and National Matters (Series 72)
1922-1943 (bulk 1922-1935) Parks Department Correspondence (Series 69)
1922-1961 Department of Social Services: Family and Child Welfare Division Reports (Series 173)
1922-1962 Park Commission Minutes (Series 91)
1922-1969 (bulk 1924-1932) Parks Department Administrative Records (Series 70)
1922-1972 (bulk 1922-1954, 1962-1968) Parks Department Contracts and Agreements (Series 280)
1922-1984 (bulk 1951-1969) Board of Supervisors – Charter Revision Committee (Series 388)
1922-1995 (bulk 1926-1933) Fire District Historical Records (Series 359)
1923-1965 (bulk 1923-1939) Parks Department Property Records (Series 149)
1924-1944 Pforzheimer Papers: Purchase Free Library (Series 157)
1924-1977, 1980-2003 (bulk late 1920s-early 1970s) Parks Department: Bronx River Parkway Records (Series 387)
1924-1953 (gaps) Park Commission Annual Reports (Series 96)