Interoperability and data sharing are important issues in the Geographic Information Systems (GIS) arena. The thesis examines he interoperability of GIS, establishes a theoretical framework together with associated techniques to facilitate GIS data sharing, and creates an interoperable GIS platform for transportation applications in Manitoba by applying the framework and techniques. The thesis has constructed the theoretical framework based on the need to share GIS data to facilitate transportation analysis and planning. Techniques to fulfill data sharing tasks are developed to improve interoperability at the spatial data level. The established interoperable platform supports transportation applications through more accurate, current, and interoperable GIS systems. The research enhances GIS interoperability between different data sources.