Patriotism, an individual sense of pride to belong to a country, is often considered by states important to secure citizen support. This feeling may go beyond national allegiance and shape perceptions of out-group members. While past research has studied the interconnectedness of state-sponsored patriotism, national identification, and citizens' attitudes toward immigrants, robust empirical evidence on how such factors are related remains scarce. This paper explores the mechanism through which states foster patriotism and how this, in turn, influences attitudes towards immigrants. We focus on the impact of state-sponsored patriotism through national day celebrations. To this end, we assemble a global dataset of publicly available surveys consisting of 1.8 million observations from 1985-2023. Employing an event study design to evaluate the effect of national days on patriotism, we measure exposure to the national day as the temporal difference between survey dates and these celebrations. Our analysis demonstrates that leading up to the national day, citizens feel less patriotic and remain so a few days after. This trend returns to pre-national day levels within two weeks following the event. This negative result is driven by countries with higher ethnic fractionalisation. We argue that people in more diverse societies resist submitting to the state’s national identity narrative accentuated by the national day. Instead, people unite in diversity. To substantiate this argument, we show that people in ethnically more diverse countries report more positive attitudes towards immigrants after the national day. This paper contributes to the study of patriotism, political attitudes, and migration.