While the effects of legal and institutional arrangements on political participation are well documented, little attention has been given to the potential participatory effects of one of the United States' most important electoral laws: constitutionally mandated reapportionment. By severing the ties between constituents and their incumbents, we argue, redistricting raises information costs, leading to increased levels of nonvoting in U.S. House contests. Survey data from the 1992 American National Election Studies show that redrawn citizens are half as likely to know their incumbent's name as citizens who remain in a familiar incumbent's district and, consequently, significantly more likely to roll off, or abstain from voting in the House election after having cast a presidential vote. We also show that participation rates in the 2002-2006 House elections in Texas - each of which followed a redistricting - match these patterns, with roll-off increasing 3% to 8% in portions of the state that were redrawn, controlling for other factors. The findings demonstrate that scholars and policy makers ought to be concerned with the extent to which the redrawing of congressional lines affects citizens' exercise of political voice.