A subway map is a schematic or geographically accurate representation of an urban transit network, depicting stations, lines, interchanges, and routes within a defined metropolitan area. As a GIS use case, subway mapping leverages geospatial data management, spatial analysis, and cartographic visualization to model complex underground and surface-level transit infrastructure with precision. GIS technology enables transit authorities and geospatial analysts to integrate multiple data layers — including station locations, route alignments, ridership statistics, accessibility features, and surrounding land use — within a unified geographic framework. Using coordinate reference systems and topological network modeling, GIS platforms support accurate spatial relationships between transit nodes and real-world geography, facilitating both schematic simplification and true-to-scale mapping outputs. Practical benefits include enhanced network planning, optimized route analysis, improved passenger wayfinding, and data-driven infrastructure decision-making. Additionally, GIS-powered subway mapping supports interoperability with urban planning datasets, enabling analysts to assess transit accessibility, identify service gaps, and model the socioeconomic impact of network expansions — making it an essential tool in modern smart city geospatial workflows.