Regional Fertility Patterns in the United States: Convergence or Divergence?

Abstract

Birth expectations data frequently are used in population projections. A common assumption in preparing sub-national population projections is that the completed cohort fertility rates of the areas in question will converge over time to a level equivalent to the prevailing average number of lifetime births expected nationally by women in the principal reproductive ages. This paper examines whether such an assumption is justified for the United States. Although there is little supporting evidence for any convergence in state fertility rates for the period 1940 to 1977, birth expectations data for women 18 to 29 years old for 1977 and 1978 indicate a fairly uniform expected family size of two children per woman. The reliability of these expectations data are examined in light of the currently low period fertility rates.