This paper analyses the role of Mompox in New Granada's interregional trade during the late colonial period. It focuses on the value, structure and destination of exports of domestic goods from Mompox to markets on the Atlantic and the Andes. By unearthing unexplored sources, this paper provides evidence that will help to understand, indirectly, some issues such as the nature and timing of economic growth, the degree of regional specialisation and, above all, the role of inland ports in the economic geography of the viceroyalty. The paper contends, first, that the region experienced a boom–bust cycle during the late colonial period. The export of domestic goods doubled between 1770 and 1800 but subsequently collapsed during the 1802-1809 years. Second, evidence suggests that the region experienced a process of market deepening and widening. Trade flows, then, played a larger role in shaping the economic history of the region than previously thought.