The experience of enslaved Africans in the Atlantic crossing redefined the meanings of the nomenclature emerging from the slave trade. Under violent conditions, captives developed networks with shipmates on board slave vessels. These ties survived for decades if shipmates stayed together in the same region, as they did in Montevideo. Shipmate ties represented a living connection for Africans not only with their experience in the Atlantic crossing but also with their homelands. Shipmates provided support to their fellows when they needed trusted associates, as the marriage files of Montevideo clearly demonstrate. Enslaved Africans commonly asked fellow shipmates to testify about their past when marrying into the Catholic Church. Marriage files contain data on the routes Africans took across the Atlantic and the Americas. They indicate the origins of the groom, bride, and witnesses, their shared itineraries, and how these itineraries changed over time. Thus they reveal patterns of geographical mobility and networks created by common experiences. Marriage files can be easily quantified, which allows us to track historical trends. At the same time, each file offers a unique story. A close reading of these stories contextualizes the experiences of slaves in the Catholic Americas and underscores common patterns in ways that lie beyond quantification.