A race-based slavery system evolved not fully before the 1700s. The transatlantic slave trade had its heyday in the 1700s and the first years of the 1800s. In 1775 amounted Africans up to 20% of the population in the American colonies, and was the second largest ethnic group after the English. After the introduction of new slaves was banned in 1807, continued the slave trade within the United States, both with imported slaves, but also with children who were sold as slaves. It was quite common that white slave owners or attendants put children at black women, to make more slaves. Children of slave women were automatically slaves. In the United States developed the so-called one drop rule itself, which meant that anyone with visible black descent was regarded as "Negroes."