We study the economic impact of world trade on the throughput in the Port of Rotterdam and the regional economy of Rotterdam-Rijnmond. We use a two-step approach. In the first step we analyze the relationship between world trade and the port's throughput. In the second step we deal with the impact of the port's throughput on regional economic indicators like income and number of jobs. It appears that the global business cycle determines the port activities and that, in turn, the port activities are essential for the regional economic development, in this way linking the regional economy to the global business cycle. Diversification of the regional economy is recommended to make the regional economy more resilient.