Cross-border migration has increased rapidly in recent decades. In response, most democracies have extended voting rights to their citizens abroad. Nevertheless, expatriate voter turnout tends to be low. This article investigates a frequently proposed remedy—internet voting—based on a case study of extended internet voting trials in eight Swiss cantons. For causal identification, I exploit an unexpected federal intervention that led to a temporary suspension of internet voting in four of the eight cantons, during which expatriates could vote only by mail. Using difference-in-differences estimation, I find that the temporary suspension of internet voting decreased turnout among registered expatriate voters by 4.1 to 6.4 percentage points. Placebo tests suggest that pre- and post-suspension trends in expatriate voter turnout were close to identical in treated and control cases. Overall, the results of this study suggest that internet voting represents an effective method to increase electoral participation among citizens abroad. Still, expatriate voter turnout remained well-below domestic turnout even with internet voting available, suggesting that high voting costs are not the only reason why citizens abroad tend to vote at lower rates.

近几十年来，跨境移民迅速增加。作为回应，大多数民主国家将投票权扩展到其海外公民。然而，外籍选民的投票率往往较低。本文基于对八个瑞士州的扩展互联网投票试验的案例研究，对一种经常提出的补救措施-互联网投票进行了研究。为了确定因果关系，我利用了意外的联邦干预，该干预导致八个州中的四个州的互联网投票被暂时中止，在此期间，外籍人士只能通过邮件投票。使用差异估计，我发现暂时中止互联网投票将登记的外籍选民的投票率降低了4.1个百分点至6.4个百分点。安慰剂测试表明，外派选民投票前后的悬浮趋势在治疗和对照病例中几乎相同。总体而言，这项研究的结果表明，网络投票是增加海外公民参与选举的有效方法。尽管如此，即使有互联网投票，外籍选民的投票率仍然低于国内投票率，这表明高昂的投票成本并不是海外公民倾向于以较低税率投票的唯一原因。