This dissertation explores the early digitalization in Sweden. As host to the first summit on the environment in Stockholm 1972 (UNCHE), as leading procurer of computer equipment as well as initiator to the world's first national Data Act of 1973, Sweden pioneered domains that have since emerged as critical to our age: environmental challenges and digital technology. Both products of the 1970s, environmental monitoring and population surveillance have typically been studied as separate phenomena. This thesis insists that they belong to the same lineage of procedures. In an effort to move beyond both celebratory and repressive discourses of technology, it turns to the infrastructural and operational aspects of histories of data. Crucially, the investigation traces a series of changes within the cultural techniques of modelling, linking and reuse. In so doing, it positions itself at the intersection of environmental and digital humanities, and contributes to both research fields. The aim of the investigation is to demonstrate how the handling of data shaped the environment and the population as objects of knowledge and to examine its consequences for state administration. By "following data" – noting how they were collected, transformed, played with, transferred, encrypted, stored and erased – the material and procedural elements of historical undertakings are emphasized. The investigation is organized in three parts: environment, population, and administration. Seeking the system dynamics origins of the 1972 Stockholm conference and the cybernetic principles of the systems ecology within the International Biological Program (IBP), the first part attempts to look past the politics of environmental movements and turns, instead, to modelling as a critical operation. The second part questions the generic surveillance studies approach to the 1970 census taking (FoB 70) and privacy debate in Sweden by considering these as part of the longer history of linking. Centering on an archival statistics system (ARKSY), a newspaper coupon campaign and the "deep map" of early computer cartography, the thesis here locates a shift from privacy as a vulnerable trait protected by law to a matter of database administration with citizens as managers of their own data. The third and final part is framed by operations of reuse. Such operations, the dissertation maintains, materialized as instrumental not only to household waste management but also to the handling of data in offices and archives. Scrutinizing test environments for word processing in the Swedish Parliament and the work of the Data Archiving Committee (DAK), the investigation argues that they should be understood as sites of reuse and recycling rather than as locations of paperless exchange. With early digitalization, the environment and the population started to emerge as "problems of data". Data were typically demanded in "raw" format and routinely portrayed as a new type of natural resource. In this setting, infrastructures of reuse proved more fundamental than imperatives of surveillance. Markedly, the manual aspects of "automatic" data processing (ADB) were downplayed even as they remained indispensable. Cycles of data appeared in many guises: in the natural environment, in models, in mapping systems, in archives. Guided by the analytical power of cultural techniques and drawing on a wide range of materials, this investigation is a prehistory of our data-driven world. QC 20230125