As homeland security policy makers seek to funnel scarce resources to the most vulnerable areas, geographic impact studies have become ever more crucial since the events of September 11, 2001. In the sense that the Los Angeles and Long Beach ports are among the largest in the world, service interruptions there would have nation-wide economic impacts. Because foreign and domestic imports are in greater volumes than exports, the interruption of imports should be examined with a supply-side MRIO-type model. Hence, a new supply-side National Interstate Economic Model (NIEMO) yields extra information with important political implications – in addition to the previously estimated demand-side results – because both simulations show that terrorist attacks in one state have significant economic impacts in other states. Especially in the U.S. Senate where political power is evenly distributed among the states, the supply-side and demand-side results could help garner nationwide support for prevention measures in specific places, often distant from the states where the measures are taken.