The cross-sectional and secular variations in the fertility of the white population in pre-Civil War Ohio are analyzed with special regard to the role of population pressure in conditioning these patterns and trends. Other factors, such as urbanization, education, cultural heritage, and the sex ratio, all of which are often cited as major explanatory variables during the demographic transition are also introduced. Although each of these variables is shown to have some impact, none can account for more than a minor proportion of the Variance in human fertility. It appears that the major force affecting both inter-county fertility and the secular trend for the state was the Variation in the degree of population pressure as measured by the average assessed value of an acre of non-urban land.