This present study explores the relationships between two adjacent metropolitan centers, Jakarta and Bandung, over the past ten years. The merging process between both of the metropolitan areas has been forecasted by many studies, yet the variables that lead to the process are still not very clear. The present article attempts to fill the gap by undertaking two approaches. First, it measures the relationships between Jakarta and Bandung by looking at the flows of people, investment and commodity. Second, it examines the implications of the relationships between both urbanization centers to the corridor area between them. It is found that over the past ten years there has been an intensifying relationship between Jakarta and Bandung in the flows of people, investment and commodity. At the same period, a rapid urbanization process has also been occurring in the corridor area between both metropolitan centers. There are both direct and indirect relations between these two geographical phenomena which finally lead to the emergence of the Jakarta-Bandung mega-urban region.