This article draws attention to the archive generated by the programme of hydroelectric construction in the Scottish Highlands between the 1940s and the 1960s. As well as minutes and reports, the archive consists of a large amount of visual material, including ‘general impressions’ depicting proposed infrastructure in its setting. This significant collection addresses current interest in ‘rural modernism’ by shedding light on the architectural history of the Highlands in the middle of the twentieth century, including the ways in which questions of style and materials were debated. It also attests to the role of infrastructure in a broader state-led programme of modernisation in twentieth-century Scotland, complementing existing studies of urban interventions and the new towns.