Essays on Macroeconomics and Population Growth

General equilibrium models are used to explore the interactions between macroeconomics and the two components of population growth: natural increase and net-migration. The first questions at hand are: What caused the baby boom? Can it be explained within the context of the decline in fertility that has occurred over the last 200 years? The hypothesis is that: (i) The decline in fertility is due to the rise in real wages that increased the opportunity cost of children; and (ii) the baby boom is explained by a burst of technological progress in the household sector. A model is developed and found to account well, quantitatively, for both phenomena. Chapter 2 focuses on some facts characterizing the U.S. economic development in the 19th century. These facts are: (i) The Westward Expansion; (ii) the accumulation of productive land; and (iii) the wage gap in favor of the West. A two-locations model is developed. A novelty is the presence of a fixed amount of land, initially unsuitable for production, but that can be improved. Historical evidence is used to calibrate the model's parameters. It accounts for the regional distribution of population and the path of the stock of productive land. The main factor driving the Westward Expansion is population growth. Chapter three asks: What drove western population growth in the U.S. during the 19th century? The facts are: (i) Natural increase was higher in the West than in the East; and (ii) in the early stages of the settlement process, net migration could account for up to 80% of population growth in some regions. A general equilibrium model is proposed, with three ingredients: endogenous fertility, investment in land, and migration. The relative abundance of land in the West promotes higher fertility. The model is simulated. It accounts well for the time-series decomposition of population growth between migration and fertility.