Bolivian migration in borax and sulphur high-altitude mining was fundamental in sustaining industrial capitalism in northern Chile. In this paper, we quantify and characterize Bolivian migration in the border mining camps of the municipality of Ollagüe, through the analysis of 335 migratory files, dating from 1888 to 1946. We focus on the Bolivian presence in eight villages and camps involved in sulphur and borax mining. We present the entry periods of Bolivian workers, as well as their origin, trade and profession, gender, marital status, age, and literacy. Results give an account of the central role played by the Bolivian migrant labour force for the development of non-metallic and high-altitude mining industries in the region. It is concluded that the capitalist expansion in the Chilean border was sustained by an ethnic subsidiarity of an international subordinate workforce.