This paper examines the interface between port cities, urban regions and their transportation systems with respect to Singapore. The development of the regional Singaporean transactional space incorporates the province of Johor in Malaysia and the Riau islands in Indonesia, with the resulting spatial pattern and linkages forming an Extended Metropolitan Region (EMR). An EMR spatial model is presented in which transportation is a key factor. This model explains four processes of territorial development — densification, dissemination, extension and contraction. Densification is a process of spatial accumulation of economic activities within an area and aims at higher levels of productivity. Dissemination is a spatial relocation of unproductive economic activity towards productive areas. Extension is a space/time collapse enabling economic activities to extend over a large territory while maintaining low distribution costs. Contraction is a rationalisation of distribution systems facing growing transportation costs and competition from other systems. Based on the framework provided by the spatial model and available evidence, an assessment of transportation and territorial development in the Singapore EMR is undertaken. The analysis underlines the role of Singapore as a regional transhipment centre and its maritimefland interface function.