Source: adapted from E.J. Taaffe, H.L. Gauthier and M.E. O'Kelly (1995) Geography of Transportation, Second Edition, Upper Saddle River, NJ: Prentice Hall, p. 223.

Chicago's beta Values for Air Transportation, 1949-1989

Technological innovations had impacts on the friction of distance, which is reflected in the reduction of the beta exponent of spatial interaction models. In this example, the emergence of jet planes had significant impacts on the reduction of the beta exponent in the 1960s. Improved speed and capacities made air transportation more affordable and air travel (interactions) increased substantially.