In addition to providing a framework for publishing a wide variety of demographic and economic data, geography also plays a critical role in the management of census field operations. Before the innovation of geographic information systems, the process of defining and mapping sub-county enumeration areas was entirely dependent on paper maps collected from local governments. These maps were copied and modified using manual cartographic techniques and were prone to error in coverage, content, accuracy, and timeliness. These challenges were not insignificant and contributed to non-sampling error in the enumeration process. To solve these problems and several others, geographers within the Geography Division of the Census Bureau designed and built a first-of-its-kind digital mapping system. This article describes the system and how, for the 2020 Census, its data will facilitate an enumeration process with a level of detail never before possible.