In health disparities research, Geographic Information Systems (GIS) provide nurse researchers with powerful tools to incorporate spatial factors, such as access to care and related attributes like socioeconomic and environmental characteristics, into their studies. This article educates nurse scientists about GIS-based research benefits and considerations (focusing on access-to-care factors) and the influence of various access-to-care metrics on research outcomes. We present an overview of GIS in nursing and health disparities research, along with findings from our 2022 study examining access to care's relationship with county-level mortality rates in Tennessee, especially in areas where rural hospitals closed between 2010 and 2019. We highlight three distinct access-to-care measures (Euclidean distances and road network-based travel times based on county and census tract centroids), showcasing how different calculations impact our modeling results. Our results underscore the importance of understanding the choice of access-to-care metrics in GIS-based research to draw valid conclusions.