In the British colonies in North America and in the United States before the abolition of slavery in 1865, free Negro or free Black described the legal status of African Americans who were not enslaved. The term was applied both to formerly enslaved people (freedmen) and to those who had been born free (free people of color). Slavery was legal and practiced in every European colony in North America, at various points in history. Not all Africans who came to America were slaves; a few came even in the 17th century as free men, as sailors working on ships. In the early colonial years, some Africans came as indentured servants who were freed after a set period of years, as did many of the immigrants from Europe. Such servants became free when they completed their term of indenture; they were also eligible for headrights for land in the new colony in the Chesapeake Bay region, where indentured servants were more common. As early as 1678, a class of free black people existed in North America. Various groups contributed to the growth of the free Negro population: children born to colored free women (see Partus sequitur ventrem) mulatto children born to white indentured or free women mixed-race children born to free Native American women (the emancipation in the 1860s) freed slaves slaves who escaped from their enslavers As described above, descendants of free Blacks who were never enslaved Black labor was of economic importance in the export-oriented tobacco plantations of Virginia and Maryland, and in the rice and indigo plantations of South Carolina. Between 1620 and 1780 about 287,000 slaves were imported into the Thirteen Colonies, or 5% of the more than six million slaves brought from Africa. The great majority of transported enslaved Africans were shipped to sugar-producing colonies in the Caribbean and to Brazil where life expectancy was short and slave numbers had to be continually replenished; this could be done at relatively low costs until the Slave Trade Act 1807.