Memorandum from David D. Lowman, Special Assistant to the Director for Congressional Reviews to the Special Assistant to the Secretary and the Deputy Secretary of Defense, "Preliminary Statement of Robert J. Tracy before the Senate Select Committee on 24 September 1975," 26 September 1975, Secret, excised copy
National Security Archive
A 1975 NSA memo on the ‘Rhyming Dictionary’ reveals how the agency indexed millions of names and began transferring that power to the CIA amid rising congressional scrutiny.
Source: Memorandum from David D. Lowman, Special Assistant to the Director for Congressional Reviews to the Special Assistant to the Secretary and the Deputy Secretary of Defense, "Preliminary Statement of Robert J. Tracy before the Senate Select Committee on 24 September 1975," 26 September 1975, Secret, excised copy Date: Sep 26, 1975 Collection: National Security Agency Tracking of U.S. Citizens – “Questionable Practices” from 1960s & 1970s Sep 25, 2017
Editorial Analysis
Original analysis by the DriftSeas editorial desk. The complete primary-source document, transcribed from the National Security Archive scan, appears in full below.
A Forgotten Index of Names
The memorandum dated 26 September 1975 is a routine‑looking internal NSA note that, once stripped of its classified enclosures, reveals a slice of the agency’s massive biographic‑information apparatus during the Cold War. Drafted by David D. Lowman, Special Assistant to the Director for Congressional Reviews, it forwards the "Preliminary Statement" of Robert J. Tracy—then chief of the Central Security Service’s International Information Division—to the Secretary and Deputy Secretary of Defense. The purpose was to supply the Senate Select Committee on Intelligence with a concise briefing on the so‑called “Rhyming Dictionary,” a tool that had become a flashpoint in the 1970s investigations of U.S. signals‑intelligence (SIGINT) practices.
The document was produced in the immediate aftermath of the Church Committee hearings (1975) and the subsequent Senate Select Committee on Intelligence, both of which were probing the scope of domestic surveillance. Lawmakers demanded concrete examples of how the National Security Agency organized and accessed personal data. Tracy’s statement, as reproduced in Lowman’s memo, was intended to satisfy that demand while also demonstrating that the agency was already winding down a controversial program.
The Rhyming Dictionary in Context
The “Rhyming Dictionary” was not a literary reference but an exhaustive index of personal names that appeared in intercepted communications. Initiated in 1945, it evolved from punched‑card logs to magnetic‑tape databases, eventually cataloguing 1.67 million entries, of which roughly 73 000 were U.S. citizens. Analysts used the index to resolve misspellings, fill gaps in garbled text, and even reverse‑spell surnames to crack coded messages. In practice, a cryptanalyst confronting a fragment of a Soviet telegram could query the dictionary, retrieve a likely name, and then trace that individual’s profile in the Central Information Biographic Files, which spanned more than 150 countries.
By the early 1970s the dictionary’s utility was waning. Project MILLSTREAM—a joint NSA‑CIA effort from 1970 to 1973—systematically transferred biographic‑support responsibilities to the CIA’s Office of Central Reference. The memorandum notes that the final batch of entries was microfilmed in 1958, and the index was formally terminated in December 1973 because “no new information was entering the files.” The timing is significant: the shutdown coincided with growing congressional scrutiny and internal NSA assessments that duplicated biographic services were inefficient and potentially illegal under emerging privacy standards.
What the Memo Reveals About Agency Culture
Lowman’s memo is terse, but its phrasing betrays an institutional awareness of political risk. The opening line—"As requested by Mr. Fred Ward, Court Reporter, inclosed is the Preliminary Statement…"—shows that the agency was carefully documenting its compliance with a congressional subpoena. The repeated handling instructions—"HANDLE VIA COMINT CHANNELS ONLY" and "NO FOREIGN DISSEM"—underscore the sensitivity attached to even a seemingly mundane index.
The document also illuminates the bureaucratic choreography of inter‑agency cooperation. The discussion of Project MILLSTREAM details a step‑by‑step transfer: a 1968 feasibility test, a 1969 formal agreement, and the gradual colocation of NSA analysts with CIA personnel. This narrative counters the popular myth that the NSA operated in isolation; instead, it was part of a tightly knit intelligence community constantly negotiating jurisdiction over data.
Legacy and Contemporary Relevance
The Rhyming Dictionary is a precursor to today’s massive data‑mining systems that aggregate personal identifiers from multiple sources. Its termination in 1973 did not end the practice of indexing individuals in SIGINT streams; rather, the function migrated to newer databases that later became the focus of the 1978 Foreign Intelligence Surveillance Act (FISA) and the 2001 PATRIOT Act expansions.
For historians, the memorandum provides concrete evidence that the NSA was already aware of the legal and ethical implications of large‑scale name‑indexing well before the Church Committee’s public hearings. It shows that the agency’s own internal reviews identified redundancy and risk, prompting a hand‑off to the CIA. The fact that the Senate committee received a "preliminary" statement rather than a full briefing suggests that the agency was still calibrating its public narrative.
In the digital age, where metadata and name‑matching algorithms drive surveillance, the Rhyming Dictionary serves as an early case study of how intelligence agencies turn raw signal intercepts into actionable human intelligence. The memo’s modest length belies its importance: it is a snapshot of a turning point when the United States began to confront the tension between national security and civil liberties—a tension that continues to shape policy debates today.
Doc ID: 6571846
SECRET
Mr Tracy
NATIONAL SECURITY AGENCY CENTRAL SECURITY SERVICE FORT GEORGE G. MEADE, MARYLAND 20755
Serial: N1120 26 September 1975
SECRET
MEMORANDUM FOR THE SPECIAL ASSISTANT TO THE SECRETARY AND DEPUTY SECRETARY OF DEFENSE
SUBJECT: Preliminary Statement of Robert J. Tracy before the Senate Select Committee on 24 September 1975
As requested by Mr. Fred Ward, Court Reporter, inclosed is the Preliminary Statement of Robert J. Tracy before the Senate Select Committee on 24 September 1975 to be delivered to Mr. Barry Carter.
David D Lowman DAVID D. LOWMAN Special Assistant to the Director for Congressional Reviews
Incl: a/s
NO FOREIGN DISSEM
SECRET
This document may be declassified
upon removal of the enclosures and physical
removal of the caveat notation.
HANDLE VIA COMINT CHANNELS ONLY
Doc ID: 6571846
Serial:
cc: DIR (Less Incl) D/DIR " ESS " ESS/R ESS (Mr. Lowman) NCRDEF (Less Incl) C52 (Mr. Tracy) L221 (Less Incl)
David D Lowman DAVID D. LOWMAN/O/ESS/x3161s/26 Sep 75/kjb
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Mr. Chairman:
I have a preliminary statement I'd like to read.
HISTORY OF RHYMING DICTIONARY
The Rhyming Dictionary is an index to the biographic files and was begun in 1945 using punched cards to record names of personalities appearing in or likely to appear in SIGINT product. From the file of punched cards, printed lists were made by forward and reverse alphabetical sort of personal surnames.
In December 1958, a machine printout of the complete Rhyming Dictionary was microfilmed for subsequent reference and a new Dictionary was begun in 1959. First occurrences of personal names were first recorded on log sheets and later transferred in batches to magnetic tapes for computer manipulation and listing as required; e.g. forward and reverse alphabetical sorts of surnames.
By mid-1973, the collection of personal names had decreased dramatically as the responsibility of providing biographic file service was transferred in phases to CIA, under implementation of Project MILLSTREAM over the years 1970-73. Thus, since no new information was entering the files and index, the useful application and maintenance of the Rhyming Dictionary became increasingly inefficient and unnecessary. It was terminated in December 1973.
[HANDLE VIA COMINT CHANNELS ONLY] [CONFIDENTIAL]
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HOW WAS RHYMING DICTIONARY USED AND BY WHOM
Created by International Information Division (C52 and predecessor organizations), the Rhyming Dictionary was an index to biographic files and served as a reference tool for researching names of personalities mentioned in communications. This information like all other data was collected and organized by C52 in order to respond quickly to the various types of requests generated by SIGINT production analysts.
The Rhyming Dictionary was used as a master index to personalities that appeared in Central Information Biographic Files which were maintained on over 150 countries and which contained the names of personalities that appeared in SIGINT plus those of personalities in collateral and open sources most likely to appear in SIGINT. The Dictionary covering the period 1959-1973 contained 1,667,396 names of which 73,141 were U.S. personalities.
In response to requests from translators, cryptanalysts and SIGINT reporters, a Central Information analyst used the Rhyming Dictionary, in its various sorts, to either complete the name of a personality when it was misspelled, or garbled or to determine his nationality which, in turn, would lead to the country file containing information on the particular individual; e.g. his location, official position, or association with activities (international travel, conferences, organizations, negotiations, conversations, and speeches of international significance). An example of another sort of the names in the dictionary was one which reversed the
[TRANSFER VIA SECURE CHANNELS ONLY]
Doc ID: 6571846 SECRET surnames--listed them backwards--which proved useful in exploiting cryptographic text containing names of personalities. This research activity by the Central Information analyst directly supported SIGINT production by enabling the cryptanalyst to: (a) identify or verify partially known elements of the text such as names of personalities; (b) recover possible verbatim texts; or (c) interpret code or cipher traffic from significant background information. Superimposed on the requirement for accuracy in research is that of speed; i.e. Central Information support must be rapid in order to assure that SIGINT is produced before losing its perishable intelligence value. The Rhyming Dictionary assisted measurably in speeding up the Central Information support to the cryptanalyst.
SPECIAL HANDLING REQUIRED [illegible]
HANDLE VIA COMINT CHANNELS ONLY SECRET
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DISCUSSIONS OF PROJECT MILLSTREAM
My understanding is that in 1967-68, an internal-NSA study was undertaken to evaluate the intelligence information support files of the Central Information Center (CIC) in order to determine the most feasible and effective system to support SIGINT processing. The study recommended that immediate steps be taken by CIC to establish closer working relationships with the CIA Office of Central Reference with a view to eliminating NSA's biographic information services and rely on CIA biographic file support via secure telephone communication. This was in line with an overall intelligence community effort to reduce duplication in biographic files.
Accordingly, arrangements were made between NSA and CIA in the second quarter 1968 to conduct a Biographic Support Feasibility Test. This test was held from July through October 1968 and thereafter it was recommended that the information resources of the Information Services Group, Central Reference Service, CIA be used to answer NSA requests for biographic information.
In April 1969, it was formally agreed between NSA and CIA to implement this recommendation by collocating Central Information personnel with CIA/CRS. Implementation was to be phased as training of Central Information (C5) personnel permitted and several C5 people were immediately detailed to CIA/CRS to learn about CRS resources and prepare for transfer of biographic responsibilities to CIA.
HANDLE VIA COMINT CHANNELS ONLY
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Accordingly, biographic information support provided by NSA was gradually phased out and transferred to CIA. In August, 1970 biographic support concerning Latin America and South America was absorbed by CIA/CRS. Answering NSA requests for Western Europe biographic support was assumed by CIA in November 1970. In February 1971, CIA/CRS began biographic support services for Africa (excluding North Africa) plus the Free-World countries of India, Pakistan, Ceylon, Japan, Indonesia, Malaysia and the Philippines. By May 1971, CIA had taken over Eastern Europe biographic support. One year later, in June 1972, NSA's needs for biographic support on Turkey, Greece and Cyprus were being provided by CIA. In another year, June 1973, biographic support to NSA on countries of the Middle East and North Africa was also being performed by CIA. Finally, in October 1973, CIA/CRS assumed responsibility for pro- viding NSA with biographic support to the [illegible] of China, Vietnam, Cambodia, Laos, Korea, Burma, and Thailand.
EO 3.3b(3) PL 86-36/50 USC 3605
[HANDLE VIA COMINT CHANNELS ONLY] [illegible]
Doc ID: 6571846 [CONFIDENTIAL] STATEMENT OF U.S. BIOGRAPHIC FILES By December 1973, these files had become inactive because their utility in answering questions had gradually diminished as Project MILLSTREAM was implemented in phases. Additionally, between early 1973 and October 1973, my Division was physically relocated three times into successively smaller work spaces resulting in a loss of 3,200 sq. ft. In turn, this loss dictated destruction of large quantities (3,000 cu. ft.) of information materials no longer considered necessary to our SIGINT support mission. Furthermore, my key researchers were collocated in an area where the files could not be accommodated. This area contained open source resource materials such as Who's Who, commercial directories, and other open source aids that are used to identify U.S. personalities. With the Division's final move and space constriction of October 1974, I consulted with Mr. Robert J. Welday, Chief, C5 concerning the possible disposition of these files. At the same time, I informed him that, when world-wide biographic information files covering the period of approximately 1940-1958 were reviewed during 1971 for final disposition, neither the NSA SIGINT producers, the NSA Historian nor CIA and DIA expressed any further requirement for such files. Therefore, Mr. Welday approved the disposal of the U.S. biographic files because: (1) they had ceased to be useful; (2) no other element had previously registered any interest in their retention; and (3) reduced work space would accommodate only the most necessary resource materials. [HANDLE VIA COMINT CHANNELS ONLY] [illegible]
NATIONAL SECURITY ARCHIVE
National Security Archive, Suite 701, Gelman Library, The George Washington University, 2130 H Street, NW, Washington, D.C., 20037, Phone: 202/994-7000, Fax: 202/994-7005, nsarchiv@gwu.edu