Economic impulses in a regional system of cities: A study of spatial interaction

King L., Casetti E. and Jeffrey D. (1969) Economic impulses in a regional system of cities: A study of spatial interaction, Reg. Studies 3, 213–218. This paper presents a model of the transmission of economic impulses through a system of cities. A partial testing of the model is attempted with respect to unemployment rates recorded in thirty-three cities in the American Midwest over the period April 1960 to September 1964. City unemployment series are regressed against the national unemployment series to obtain the city residual series (attributable to regional rather than national factors). On the residual series a lagged correlation analysis is preferred. On this basis, regional clusters of cities are identified each being characterized by strong “inter-group” interaction with no time lag and by weaker “between group” interaction with time lags.