This study attempts to determine whether cities with superior intercity highway connections enjoy more rapid manufacturing growth, i.e., whether relatively fast, low-cost motor transportation attracts industry. Manufacturing growth rates are compared for two groups of cities, an experimental group located on interstate system freeways and a control group located elsewhere. The two groups are comparable in all major respects - population, location, air service, economic activity, etc. - except highways. Comparability rests on the matched pairs procedure (106 city pairs). A city's growth is its per capita manufacturing employment increase between 1958 and 1963. Differences between group means are tested for significance for all pairs combined and many breakdowns. To clarify the relationship between growth and distance from freeway, correlations for hundreds of curvilinear relationships are compared. Nationwide, there was no significant difference in freeway and nonfreeway performance. But in regions with dense population and uneven terrain - the northeast, southeast, east midwest, and far west - freeway cities grew much faster. In these regions the freeway advantage was largely confined to cities either above 16,000 in population or served by airline, for which cities significance levels ranged as high as 0.01. The growth-distance relationship is best described by a probability curve peaking at zero miles and having a standard deviation of 5 miles: freeways have little effect on cities more than 10 miles away.
Abstract