Natural history collections are tremendous assets for research (and teaching) in environmental and health sciences. Because these collections have been developed primarily for studies focused on biodiversity discovery, it remains unclear how this infrastructure will enable assessments of critical scientific questions related to environmental change. Recent specimen digitization efforts present an emerging opportunity to critically evaluate existing infrastructures and assess their temporal and spatial coverage. Using digitized records from VertNet of US mammal collections, we identify opportunities and limitations for investigating spatio-temporal changes in mammals and their communities. From these key resources, we emphasize the need for a comprehensive plan for increased sampling of mammalian diversity to maximize research into the future and foster an improved understanding of essential interactions among organisms and between them and their environments.