American economic growth from colonial times to present has always been driven by population growth. There are three factors that trigger population growth in America; birthrate, death rate and immigration. The will be focus on birthrate and death rate in the colonial period. Birthrate in earlier America was determined by people marrying at an early age and as noted by Beaujour, a former French Consular Official to the United States in1814, marriages in America were much easier than Europe because the means of substance was in abundant. As a result Americans have the liberty to raise a family the size of their preference because of the lack of motivation to limit human reproduction. Birthrate had noticeably fallen throughout the course of the nineteenth century the birthrate was almost halved, falling to thirty per thousand by 1909 and dropping below twenty per thousand in the 1930s and in recent times. (Atack Passel)
The nineteen century birth decline can be attributed to the differences and how and where people lived. But the real explanation to birthrate is the access to land, since agriculture was the main source of employment and real estate the major source of wealth in America in the first three quarters of the nineteenth century, therefore, land constituted an economic prospect for most people. The thought of having large families was discourage by urban overcrowding in urban areas along with the growth of the industrialization that opens doors and create employment opportunity for women outside the home. As a result the opportunity cost of having children was raised.
As explain in Atack and Passel land opportunity was in abundant on the growing frontier and entry costs were very low. The clearing of land to make farm on the frontier involve large inputs of labor over a number of years and the pattern of crop cultivation and animal 20husbandry created numerous employment opportunities for family members of all ages therefore increase the demand for labor on the frontier. This was reflected in the high wages and numerous complaints of labor shortage at the time. For the farm family the only way to resolve this problem was by producing its own labor force just as it produced its own work supply and livestock. At the start of the nineteenth century entry for the Northeast was controlled because of land shortage. In the south economic opportunities were less accessible because slavery created a barrier to entry into the most money-making southern farming. While the link between land accessibility and economic prospect seem clearly recognized, a generally adequate measure of land has proved to be vague. Cropland was one of the measures in 1949 to measure land accessibility in the pre-civil War America and by the number of farm in 1880. Fertility rate begin to decline in 1860 not long after intensive settlement begin, perhaps when 20 to 40 percent of the cultivable farm land began was settled. Farmers in the nineteenth century were more well- to-do for the most part in the current wealth distribution. They were more interesting in preserving their wealth than dispersing it. A typical farm was family own by many generations and the inheritance was equal by all blood tie relative. Children did contribute to farm production by the age of seven to twelve teenage male were just as valuable in the more settled areas. The idea was that children from the frontier was expected to be more valuable because there more all kind of opportunities there. As the idea that children would stay around to care for parent in old age decreases, the value that parent put on children as security decreases as well. As a result rational parent would change the norm by having fewer children. Women in their mid to late thirties stop having children and postponed early marriages until late in life. Hence, the fertility rate was reducing by limiting the number of children a woman could bear.

Death Rates

In the colonial period there was no system of nationwide registration of births and deaths until the 1930s. This makes it lesser problem estimating birth versus death rates, birth could be estimated by the presence of a person, while deaths were simply marked by inexplicable absence of an individual. As a result less is known about crude death rates than crude birthrates. In the 1700 the death rates was about forty per thousand and the natural rate increase of the population was about 1.5 percent. Death rates for white had fallen more than 40 percent to about thirty-three per thousand. In the 1900 the natural rate of increase of the population fell about 1.3 because both death and birth rates had significantly dropped. This drop in mortality can be attributed to the wide-ranging age of the population in the nineteenth century and on. This shift can affect the crude death rate because persons in each group age have disparity risk of dying, whether from aging, malady, childbirth or accident. Life expectancy began to increase as improvement of sanitation in the provision of safe water and milk supply. Children by the age of ten no longer face a greater threat to life. Another reason for the decline in death rate was the improvement in medical care and knowledge, and improvement in personal hygiene and sanitation. Most the public health changes were taken place in rural areas.

Passell, A. &. (1994). A New Economic view of American History. New York: Norton & Company, Inc.