The Spatial Diffusion of Fertility: A Cross-Sectional Analysis of Counties in the American South, 1940

In recent years the diffusion perspective on variation and change in levels has attracted increasing interest. Yet few researchers have attempted to estimate the effect of diffusion on geographic variations in fertility. The author has employed a spatial-diffusion model to assess the effect of diffusion in shaping variation across 1052 counties in the American South in 1940. Variation in levels and the fertility for each county are measured. Fertility potential is a spatial-effects variable that summarizes each countys geographic proximity to the influence of other high- or low-fertility counties. A two-stage least squares technique described by Land and Deane (1992) is used to assess the effects of potential on observed levels. A significant diffusion effect is inferred. The diffusion effect withstands the introduction of control variables measuring a variety of other characteristics of southern counties many of which themselves have significant effects on actual levels. The author concludes that inter-county variation in in the South was shaped by a mix of social forces especially structural and diffusion processes. (authors)