Measuring European integration as boundary formation—The EUROBORD dataset

This article introduces the EUROBORD dataset. Starting from a Rokkanian conceptualization of polity formation as boundary formation, we propose a novel measurement of European integration as a combination of boundary closure and boundary control. We measure integration annually across 48 functional boundaries based on a coding of European Union (EU) law. By comparing our measure with existing measures of European integration, we provide support for its convergent validity and demonstrate its value added. We further present descriptive analyses of the historical development of the EU boundary and polity formation and propose a unified measure of European integration combining boundary control and boundary closure. The EUROBORD dataset offers the most comprehensive and fine-grained measure of European institutional integration to date.