If the framers of the U.S. Constitution thought that the census might be viewed as an intrusion on personal privacy or foresaw any need to keep census data confidential, their misgivings were not evident when they approved Article 1, section 2, providing for a decennial census. Confidentiality and privacy may not have been an issue then since the first enumeration in 1790 collected minimal information and only produced statistics needed by the Federal Government for a few specific purposes, such as—

• Reapportioning seats in the House of Representatives
• Levying direct taxes on each state based on its population
• Determining the country’s military potential in case of war

Only later, as the amount of data collected became more extensive, would census officials gradually become aware of the public’s privacy concerns and the need to establish confidentiality safeguards that today are an integral part of census-taking operations.

By 1850 however, the need for information had expanded and Federal Government officials, statisticians, and others saw the census as a means of gathering more information on a growing number of demographic (people) and economic (business) topics.¹ Consequently, as the number (and sensitivity) of questions in the census increased, so did the potential for abusing privacy (an individual’s or business’ interest in personal or proprietary information weighed against the Government’s need to know) and confidentiality (the Government’s responsibility not to disclose individual census information to anyone else).

Although the concepts of privacy and confidentiality are difficult to separate, most of this monograph’s focus is on the confidentiality of census information and its historical evolution between the 1790 and 2002 censuses.² Since the American public’s privacy concerns are of more recent origin, dating back to the events in the 1960s and early 1970s that lead to the Privacy Act of 1974, the Census Bureau’s historical response to these concerns is briefly dealt with in the last section.

The monograph includes the following four sections—

1. The Growing Need for Confidentiality Safeguards. This section traces (more or less chronologically) the evolution of confidentiality safeguards between the 1790 and 1980 censuses—starting with the absence of these safeguards, continuing through the enactment of Title 13, United States Code, the protection of individual census records, and concluding with the U.S. Supreme Court’s decision stating that even address listings are confidential.
2. Disclosure Limitation at the Census Bureau. In addition to assuring the confidentiality of individual census records, the Census Bureau uses disclosure limitation to prevent the identification or harm of any person or establishment from its published consolidated data. This section discusses how disclosure limitation works, its history at the agency, its most recent applications during the 1990 and 2000 censuses, and concludes with the oversight provided by the Disclosure Review Board.
3. Restricted Access to Confidential Data. This section describes the confidentiality measures put in place by the Census Bureau’s Center for Economic Studies (CES) since 1994 to enable researchers to use economic microdata at seven offsite Research Data Centers (RDCs) located around the country.
4. Privacy at the Census Bureau: 1974 - 2002. This section briefly describes what has transpired at the Census Bureau since the passage of the Privacy Act of 1974, the agency’s internal structure for establishing privacy policy, and privacy research already conducted and now underway.

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¹ Margo J. Anderson, The American Census: A Social History, Yale University Press, New Haven, CT, 1988.

² This monograph was concluded shortly before the data-collection process began for the 2002 Economic Census.