Despite the widespread scholarly attention given to get-out-the-vote tactics the
recent one and a half decade, few have studied the effect of short text
messages (SMS) on voter turnout, and no previous such study has been
conducted outside the US. We analyze four SMS experiments with more than
300,000 voters conducted in relation to two elections in Denmark and find
intention-to-treat (ITT) effects between 0.33 and 1.82 percentage points with a
pooled effect of 0.74 percentage points. Furthermore, we vary the timing and
the content of the messages to test existing theories of text messages as
mobilization tools. In one experiment, we find messages delivered before
Election Day to have a higher effect than those delivered on Election Day, while
we find no additional effect of delivering multiple messages. We also vary
message content and in general find no significant differences from sending
different messages.