population rose to a quarter of a million during the 17th century, and to nearly 2.5 million on the eve of the American revolution. The estimates do not include the Indian tribes outside the jurisdiction of the colonies. Good health was important for the growth of the colonies: "Fewer deaths among the young meant that a higher proportion of the population reached reproductive age, and that fact alone helps to explain why the colonies grew so rapidly." There were many other reasons for the population growth besides good health, such as the Great Migration. By 1776, about 85% of the white population's ancestry originated in the British Isles (English, Scots-Irish, Scottish, Welsh), 9% of German origin, 4% Dutch and 2% Huguenot French and other minorities. Over 90% were farmers, with several small cities that were also seaports linking the colonial economy to the larger British Empire. These populations continued to grow at a rapid rate during the late 18th and early 19th centuries, primarily because of high birth rates and relatively low death rates. Immigration was a minor factor from 1774 to 1830. According to the United States Historical Census Data Base (USHCDB), the ethnic populations in the British American Colonies of 1700, 1755, and 1775 were: Slavery Slavery was legal and practiced in all of the Thirteen Colonies. In most places, it involved house servants or farm workers. It was of economic importance in the export-oriented tobacco plantations of Virginia and Maryland and on the rice and indigo plantations of South Carolina. About 287,000 slaves were imported into the Thirteen Colonies over a period of 160 years, or 2% of the estimated 12 million taken from Africa to the Americas via the Atlantic slave trade. The great majority went to sugar colonies in the Caribbean and to Brazil, where life expectancy was short and the numbers had to be continually replenished. By the mid-18th century, life expectancy was much higher in the American colonies. The numbers grew rapidly through a very high birth rate and low mortality rate, reaching nearly four million by the 1860 census. From 1770 until 1860, the rate of natural growth of North American slaves was much greater than for the population of any nation in Europe, and was nearly twice as rapid as that in England. Religion Protestantism was the predominant religious affiliation in the Thirteen Colonies, although there were also Catholics, Jews, and