Consider the following facts. In 1950, the richest countries attained an average of 8 years of schooling whereas the poorest countries 1.3 years, a large 6-fold difference. By 2005, the difference in schooling declined to 2-fold because schooling increased faster in poor than in rich countries....

How important was international immigration for the U.S. and its demography during the nineteenth century? This paper investigates, quantitatively, its effect on the westward movement of population and the regional and secular changes in fertility. Beside immigration, two alternative forces are...