Truman defeats Dewey: The effect of campaign visits on election outcomes

Political science research suggests that campaign visits by presidential candidates produce small and short-lived effects, consistent with mixed findings of their influence on election returns. We argue that existing studies are constrained by two issues: most studies rely on state-level data, rather than more localized data, and do not incorporate differentiation in the quality of campaign appearances in their assessment of visit effects. To incorporate these concerns in a study of campaign visit effects on election outcomes, we study the 1948 presidential election, during which Harry Truman engaged in a major whistle-stop train tour and won a surprise victory over his opponent, Thomas Dewey. Using data on campaign stops gathered from archival sources, we estimate the effect of campaign appearances on candidate vote share at the county level. We find that Truman, on average, gained 3.06 percentage points of the overall vote share in counties that he visited. Consistent with contemporary judgments of the “quality” of the two candidates' campaign stops, we find no effect of Dewey's appearances on his performance. Our results provide strong evidence that candidate visits can influence electoral returns, rather than merely affect short-term public opinion. In counterfactual simulations, we show that Truman's extensive campaign tour likely won him the state of Ohio, highlighting the importance of strategic campaign decisions and campaign effects in close elections.