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FBI Central Records System

Most FBI records in the National Archives come from the Bureau's Central Records System (CRS), established in 1921 and modified over the years as the Bureau took on new responsibilities. (For a brief description of records from earlier years arranged according to different record keeping practices, see Other Records.) The following is a brief overview and introduction to this recordkeeping system.

Almost all FBI records are part of a case file in the CRS. Records relating to each specific Federal crime are assigned to a numerical classification relating to that subject and other administrative materials are assigned to numerical classifications established for those types of records. For example, records resulting from investigations relating to the May Act, which was intended to prevent prostitution in restricted zones surrounding military bases, were assigned to Classification 18, and Classification 63 covers "Miscellaneous-Nonsubversive" matters.

Within each classification, the records are further divided into cases, each designated by a number. For example, Case File 18-20 would indicate the twentieth case file in Classification 18 (May Act). Within each case file, every document carries a unique serial number. Therefore a document with the marking "18-20-6" indicates the sixth document or "serial" in the twentieth case:

  • 18 is the Classification number (in this case May Act);
  • 20 is the case number;
  • 6 is the serial or individual document number (e.g. the 6th document in this case).

Generally, documents were added to a file chronologically and numbered consecutively. Within each file, the documents are organized so they are in reverse chronological and reverse numerical order. As the documents accumulated to a thickness of about one inch, a new section was opened to contain additional documents. Because cases might be active for many years, ultimately they may consist of multiple sections and include hundreds, if not thousands, of individual serials. Documents interfiled at a later time were given a serial number that included an "X". Documents or enclosures too large to be placed in the case file were assigned a serial number and placed behind the main file and are thus known as "enclosures behind the file" or EBFs. A note in the file usually indicates the existence of an EBF.

Each Classification includes both a zero (0) file and a double zero (00) file. The 00 files contain documentation on the administrative history of the classification, documenting why it was established and how it changed over time. The 0 files, established before advent of the 00 files, may contain policy documentation predating the establishment of the 00 file but generally contain miscellaneous documentation that did not warrant establishment of a case file such as citizen complaints, routine requests for information, and preliminary investigations that did not lead to more substantive action. The 00 files are designated for transfer to the National Archives; however only policy documentation and some other 0 files are so designated.

Field Office and LEGAT records are arranged using the same file classification system. While there is significant duplication between the records maintained at headquarters and those from field offices, the latter do include significant amounts of unique documentation not found in the headquarters files.

To maintain control of the records and to facilitate use of the files, the Bureau and Field Offices established extensive indices to the records. Given the organization of the records, it is extremely difficult to locate records of interest without the indices, unless you have a citation to the appropriate case file(s). Eventually, the indices to permanent records will be transferred to the National Archives. Until that time, researchers must contact the FBI to request citations (see How to Access FBI Records in the National Archives).

More information about FBI records can be found on the FBI website here and in Gerald K. Haines and David A. Langbart, Unlocking the Secrets of the FBI: A Guide to Its Records and Classification System, Wilmington, DE: Scholarly Resources, 1993.

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The U.S. National Archives and Records Administration
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