Mechanising migration: Transnational relationships, business structure and diffusing steam on the Atlantic

Abstract

The diffusion of steam into the transatlantic migration system of the nineteenth century, one of the most important developments in the history of human demography, is often explained by the technical progress of ships, which made the carrying of migrants under steam profitable. Existing historiography posits that early, basic paddle steamers were sustainable only with government mail contracts, whilst iron screw steamers later facilitated the emergence of a mass migrant trade. Data on steam company formation, durability and accounting for the mid-nineteenth century show that technical thresholds are not sufficient to explain the transfer to steam shipping of migrants. Determining factors were inter-regional relationships connecting engineering and demographic change, and, critically, the abandonment of capitalising novel steam lines. This article demonstrates that steam became usable because of endogenous transfer within well-established sailing services, a pivotal strategy adopted by those connected to centres of both innovation and migration.