Abstract
<p>Local-level voting data is crucial to both electoral geography and political sociology. Yet, comparative election data is often unavailable below the regional tier, hindering fine-grained transnational analyses. To address this gap, we present the Basic Local Units Election Database (BLUE_DB). Our dataset covers 334 national and European Parliament elections across 31 European countries between 2001 and 2025, leveraging a new typology of over 150,000 local administrative units and nearly 3,900 parties, coalitions, and individual candidates.BLUE_DB is publicly available, comes with a dedicated web interface, and is accessible programmatically via dedicated Python bindings. It can be seamlessly joined with official European geodata through Local Administrative Unit (LAU) codes and to prominent party-politics datasets through Party Facts identifiers. In this paper, we describe the construction of BLUE_DB from authoritative national sources, validate it by comparison to existing regional-level datasets, and discuss its use in political science research.</p>