Interstate Voter Registration Database Matching: The Oregon-Washington 2008 Pilot Project

Working Paper No.: 
Date Published: 
Jeff Jonas
Entity Analytics
William E. Winkler

Voter registration databases maintain lists of registered voters that are used to determine who is and is not eligible
to vote in an election. As such, accurate voter registration databases form a cornerstone of the electoral process. In
the United States, each state maintains its own voter registration database. It is not uncommon for a voter to become registered in two states, for example as a result of moving from one state to the other or of living in one state and working in one another.

In this paper, we report on a pilot interstate voter registration database matching project between the two states
of Oregon andWashington whose goal was to explore the feasibility of using database matching to identify voters
registered in the two states, and to do so with as much openness and transparency as possible. We describe
the matching algorithms used, the procedures taken with found matches, and the resulting actions taken on actual
voter registrations. We also discuss several directions for improving matching algorithms and procedures.

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