Did the election of Donald Trump affect the popularity of the European Union (EU) in Europe? Theoretically, both a positive rally effect (due to a perceived external threat) and a negative domino effect (due to resignation among Europhiles and/or reinforcement among europhobe nationalists) are plausible. We treat Trump’s unexpected victory as an external shock and use a Eurobarometer survey that was conducted in all EU-28 member states four days prior to (control group) and six days after the election (treatment group) as source material for a natural experiment. The analysis reveals that the election of Trump caused a significant increase in the EU’s popularity in Europe immediately after the election. This “Trump effect” is considerable in size, roughly equivalent to three years of education. Gains in popularity were particularly high among respondents who perceived their country as economically struggling and, surprisingly, among the political right, suggesting that Trump’s victory broadened and ideologically diversified the EU’s base of support.