We report on a large-scale (randomized) field experiment we designed and conducted to assess ATMs’ (automatic teller machines) capacity to “get out the vote”. This is a heretofore unexploited method of voter mobilization. Our experimental design used the full universe of functioning ATMs in Portugal, which benefits from a sophisticated world class system, with wide national coverage. We randomly selected a set of treatment civil parishes, where a civic message took over the totality of ad time in ATMs, which we compare with a set of control civil parishes where advertisements ran as usual. The ATM campaign we follow was active for three days immediately before and during the 2017 local elections in Portugal. When we consider the intensity of treatment, for both the entire campaign period and the weekend, results show a statistically significant increase in the likelihood of voting. All three proxies for treatment intensity we employ deliver robust positive coefficients. Placebo tests using turnout rates in previous elections do not show significant coefficients, strengthening our interpretation of the experimental results.