Slavery in the US had formed a slave labor which existed as a legal institution from the early years of the colonial period. By 1804, many northern states of the Mason and Dixon Line had either abolished slavery outright or had passed many laws for the gradual abolition of slavery. In 1787 Congress prohibited slavery. In the Northwest Territory, after a proposal by Thomas Jefferson to abolish it in all the territories failed. However slavery gained new life in the South with the cotton industry. It expanded into the Southwest. The nation was polarized into slave states but also free states along the Mason Dixon Line, and separated Pennsylvania and Maryland. Chattel slavery became an ownership of human being. Most slaves were blacks of African descent and owned by whites. Freedom was only possible by running away which was very difficult and illegal to do, or by manumission by their owners, which was frequently regulated. Slave labor had been demanded in the northern and in southern cities they were servants. Majority of the slaves had worked at agriculture on plantations & even on large farms. They had been engaged in a work-gang system on large plantations. Others worked in cotton fields. In other small operations they also worked side by side with their owners. In large plantations they were directed by white paid overseers as well. In the early era of chattel slavery, there was much work organized under a system of bonded labor known as the