The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or "reaches" that comprise the nation's surface water drainage system. It provides a national framework for assigning reach addresses to water-related entities. Once linked to the NHD by their reach addresses, the upstream/downstream relationships of these entities and any associated information about them can be analyzed. The NHD is intended to facilitate the improved integration of water-related data in support of the application requirements of a growing national user community and will enable shared maintenance and enhancement. This paper presents an overview of the NHD content and applications.