This monograph is about the multi regional input-output model used in long-run simulation. The input-output technique was originally developed for spaceless, short-term analysis of a national economy. However, its high potential as an analytical tool has resulted in an expansion of its application in various directions. Thus, we now have the inter- and mul tiregional input-output model, in which a nation is broken down into a number of interacting regions, and some applications dealing with long-range projections of input-output systems. This study attempts to integrate those two directions within the framework of interregional simulation modeling. A major problem with the multiregional input-output model for long-run simulation