vestments on land use, the results of and problems with this study are summarized in detail in this section.
Statistical techniques such as analysis of variance and multiple regression were used in the study to compare the presence or absence of beltways on a variety of measures of economic impact within metropolitan areas. Results from a sample of 27 metropolitan areas with beltways were compared with results from a sample of 27 metropolitan areas without beltways. The measures were tracked over 10 years or more (depending on the availability of data and the length of time since construction of the beltways). In an attempt to determine the effect of beltways on the distribution of growth within metropolitan areas, central-city population growth was compared with that of the suburbs, and the location of housing development, manufacturing activity, wholesale employment, and retail sales was examined. In general this analysis found few statistically significant differences in development patterns in beltway and nonbeltway metropolitan areas, and the differences that were found were not large or consistent over time.
The study findings on the possible land use effects of beltways can be summarized as follows.
Central-city population: It proved hard to deduce any effect of beltways on central-city population. Regional effects (growth in Sun Belt versus Frost Belt metropolitan areas) appeared to swamp other effects.
Retail sales: The comparative increase in retail sales between central cities and suburbs was not significantly different in areas with beltways compared with areas without beltways.
Suburban housing development: The presence of beltways did not determine the rate of suburban housing development. Cities without beltways had more suburban than urban housing development, which made it difficult to argue that beltways induced residential development in the suburbs at the expense of the central city.
Manufacturing employment: For the 1967 to 1972 period, the study found that in cities with beltways, manufacturing employment in the central city lagged, whereas it grew in the suburbs.