Recent completion of detailed geologic mapping of the Albuquerque-Rio Rancho metropolitan area in Bernalillo and Sandoval County, New Mexico, delineates numerous sedimentary and igneous units that provide an updated geologic framework for hydrogeologic investigations of aquifer units that supply water to this semi-arid urban region. A GIS-based map compilation encompasses 2175 km² of the Albuquerque-Rio Rancho metropolitan area and vicinity (Connell, 2006; NM Bureau of Geology and Mineral Resources, Open-file Report 496, scale 1:50,000; http://geoinfo.nmt.edu/publications/openfile/496), and preserves nearly all of the elements of the 1:24,000 base mapping and illustrates important regional stratigraphic and structural trends that are useful in understanding regional hydrogeologic conditions. Geologic units exposed in the map area range from Proterozoic granite and schist, through modern alluvium; however, much of the geologic mapping emphasized Cenozoic features, such as the Santa Fe Group and incised alluvial aquifers. The Santa Fe Group has an estimated maximum thickness of over 5 km; however, only the upper ~650 m are exploited by water wells. Recognition of a regional (Mio-Pliocene) unconformity in the Santa Fe Group succession resolves stratigraphic correlation problems and provides an important basis for understanding the distribution of aquifer zones. The structural configuration of the basin in the map area indicates that much of the City of Albuquerque derives groundwater from the (Plio-Pleistocene) Ceja and Sierra Ladrones formations; the upper 300 m contains the most productive aquifer zones. Rio Rancho derives much of its water from the older, deeper and more consolidated (middle and upper Miocene) Arroyo Ojito and Cerro Conejo formations.