1 A number of economic explanations for the process of regional growth have been proposed in the literature. Apart from pure scholarly interest, under­ standing the factors that have promoted growth in some regions while others have been left lagging is of crucial importance for the design of policy aimed at helping "depressed" regions or promoting balanced growth among regions. The purpose of studying the process of regional growth is to delineate the variables that have the major influence on growth, to under­ stand the mechanisms through which these variables exert their forces, and to determine if the interactions of these forces alter the magnitudes of response or the manner in which a regional economy responds to stimuli. The first step in this process is the determination of the primary forces responsible for the growth or stagnation of a region. These forces should be few in number if the analyses of the mechanisms that transmit their effects and the interactions among those mechanisms are to be reasonably tract­ able. Regional economists cannot draw on many of the results of studies of the economic development of nations, for many of the forces isolated by development economists, such as culture, tradition, or barriers to free flows of goods and factors of production, have no viable role to play in the explanation of the variety of growth experience within a system of regions.