Individuals engaged in overseas trade in the early modern period often faced high levels of uncertainty regarding their prospects for trade. One way of managing uncertainty is to gather information from others through social interactions, that is, through social networks. Here we consider how social ties impacted trade patterns by analyzing the relationship between port traffic and early modern ship captains’ exposure to information about ports using informal relations. We consider the possible impact of strong and weak ties and the use of ties under different types of uncertainty. The analysis suggests that social networks encouraged trade at port cities with already high rates of traffic, though this effect is less pronounced than for other means through which information was distributed throughout the trade system.