The problem of predicting interregional commodity movements and the regional prices of these commodities has intrigued economists, geographers and operations researchers for years. In 1838, A. A. Cournot (1838) discussed the equilibrium of trade between New York and Paris and noted how the equilibrium prices depended upon the transport costs. Enke (1951) recognized that this problem of predicting interregional flows and regional prices could be formulated as a network problem, and in 1952, . Paul Samuelson (1952) used the then recent advances in mathe matical programming to formalize the...