Revisiting the uniqueness of simple demographics in the US population

TLDR

A 1990 census study found that 87 % of Americans could be uniquely identified using gender, ZIP code, and full date of birth. The paper revisits this issue with 2000 census data, providing an up‑to‑date assessment of the privacy threat posed by disclosing gender, ZIP code, and full date of birth, and aims to serve as a reference for privacy researchers. The study finds that only 63 % of the US population can be uniquely identified by those three demographics, a lower proportion than the 87 % reported in the earlier study.

Abstract

According to a famous study [10] of the 1990 census data, 87% of the US population can be uniquely identified by gender, ZIP code and full date of birth. This short paper revisits the uniqueness of simple demographics in the US population based on the most recent census data (the 2000 census). We offer a detailed, comprehensive and up-to-date picture of the threat to privacy posed by the disclosure of simple demographic information. Our results generally agree with the findings of [10], although we find that disclosing one's gender, ZIP code and full date of birth allows for unique identification of fewer individuals (63% of the US population) than reported in [10]. We hope that our study will be a useful reference for privacy researchers who need simple estimates of the comparative threat of disclosing various demographic data.