This article promotes the value of GIS methodologies to integrate and analyze a range of historic sources dating to the eighteenth century, utilizing Charleston, South Carolina as a case study. Data compiled from the 1790 Federal Census, the 1790 Charleston trade directory, and Ichnography of Charleston 1788 provide vital and complementary evidence that allows the population of the city to be located, which in turn provides a means of assessing late eighteenth-century residency patterns and the enslaved urban population. The value of data visualization is explored, underscoring the need for historians to engage with visual representations of data to communicate research results.