Nowadays, a large number of countries combine formal democratic institutions with authoritarian practices. Althoughin these countries the ruling elites may receive considerable voter support, they often use several manipulation toolsto control election outcomes. A common practice of these regimes is the coercion and mobilization of large numbersof voters. This electoral irregularity is known as voter rigging, distinguishing it from vote rigging, which involves ballotstuffing or stealing. We develop a statistical test to quantify the extent to which the results of a particular electiondisplay traces of voter rigging. Our key hypothesis is that small polling stations are more susceptible to voter riggingbecause it is easier to identify opposing individuals, there are fewer eyewitnesses, and interested parties might reasonablyexpect fewer visits from election observers. We devise a general statistical method for testing whether votingbehavior in small polling stations is significantly different from the behavior in their neighbor stations in a way that isconsistent with the widespread occurrence of voter rigging. On the basis of a comparative analysis, the methodenables third parties to conclude that an explanation other than simple variability is needed to explain geographicheterogeneities in vote preferences. We analyze 21 elections in 10 countries and find significant statistical anomaliescompatible with voter rigging in Russia from 2007 to 2011, in Venezuela from 2006 to 2013, and in Uganda in 2011.Particularly disturbing is the case of Venezuela, where the smallest polling stations were decisive to the outcome of the2013 presidential elections.