Latin America is home to a number of the largest countries powered by hydroelectricity in the world today, both in absolute and per capita levels. This region accounts for over 20 per cent of the world’s hydropower and has by far the largest share of hydroelectricity over total electricity generation in the world. Excluding China, Latin American hydropower exhibits the fastest growth in the world over the last 30 years. Despite these records, Latin America’s large hydroelectric potential began to be realised late in comparison to most advanced countries, and its advance has been notably uneven across time and space. This article provides a succinct survey of the evolution of hydropower for 20 Latin American countries over the past century and offers a unique quantitative, comparative perspective into the past and present of hydroelectricity in the region. We investigate the role played by the different domestic energy endowments in the way hydroelectricity developed across the region. We conclude that the gross theoretical hydroelectric potential is a necessary but not sufficient condition for understanding the historical evolution of hydroelectricity in different countries. We used panel data analysis to examine the role of alternative sources of energy, electric demand and each nation’s capacity to supply electricity infrastructure. Our model explicitly accounts for the effects of different gross theoretical potentials and the effect of time passage. Overall, we report that Latin American hydropower followed an uneven path over the 20th century.