National statistical agencies have the responsibility of collecting information about a nation's population and of publicly releasing this information without violating pledges of confidentiality. A statistical agency must consider the geographic detail on microdata files prior to their release. The finer the geographic breakout, the greater the risk that a respondent may be identified. In this paper, we regard the number of population uniques on a file as one component of a measure of risk and then relate this component of risk to identifiable geographic area size. The objective is to support the development of geographic area cut-offs when designing microdata release strategies.