We combined five major survey projects spanning 51 years and more than 3 million individual respondents across 28 countries to create the first comprehensive measure of European identity over time. Previous studies could not reliably compare how European identity changed because surveys used different questions, wording, and translations. We used advanced statistical modeling with individual-level data to create statistically robust country-year estimates that address these inconsistencies and enable consistent cross-national comparisons across decades.

Our new longitudinal perspective allows us to understand the relationship between European institutions and collective identities in ways that were not possible before. This represents a significant step forward in understanding important large-scale mechanisms that shape European identity across the continent and lays the groundwork for future research examining how institutions and identity influence each other.