The transatlantic slave trade which began in the 16th, 17th and 18th centuries forever changed the demographic structure of the United States. It introduced an ethnical race which was treated in ways that violate every tenet of present day United Nations human rights charter and the US law. However, such treatment of African slaves was common and lawful during the 17th and 18th centuries and slaves were mainly the source of unfree labor in the agricultural South of the United States. These very slaves who were forced to migrate from their homes in Africa became the main reason for social and political change in America. The impact of African slavery was such that America’s only civil war was fought for their liberation and emancipation. A century later the Civil Rights Movement of the 1960 caused much change in the US social structure, law and ideologies; and central to the Civil Rights Movement was the issue of ‘black freedom’.

The origins of slavery in the US can be traced to colonial America where there was an abundance of agricultural land but not enough labor. During the colonial era Native Americans and indentured servants from Europe were used as agricultural labor. However, Native Americans were inefficient and were more profitable if sold to Caribbean planters. The number of poor Europeans who served as indentured servants started declining towards the end of the 17th Century due to improved economic conditions in Europe. Also, European immigrants found that more money can be made in the North where they were taught skilled labor and worked in factories. Labor in colonial America became scarce and plantation owners especially in the South demanded another source of unfree labor, African slaves. Towards the end of the 17th Century the population of African slaves began increasing at a formidable rate and when England assumed superiority in the transatlantic slave trade the African slave population increased to 40 percent of the population in Southern mainland colonies and laws were made in 1660 which provided that black slaves and children of slave women would serve for life.

As an unfree source of labor slaves were used for various tasks but essentially they were used as agricultural laborers. African slaves worked in large numbers for big plantations which grew cash crops such as tobacco, rice, wheat and sugar for the market. In the North however, such massive use of slave labor was not made in principal because the soil and climate were not good for agriculture and most European immigrants worked in the factories in the North. By the mid 18th century more than 90 percent of African slaves lived in the South.

Another reason for the regional differences was that the English masters of plantations actively participated in the day to day running of the plantations. These slave masters stuck to plantation style farming. While the English masters became Americanized so did the African slave population. A natural growth in population of African slaves occurred after the banning of slave imports in 1808. The slave population began to increase at a phenomenal rate in the South and soon surpassed from a minority to a majority in population.

Slave masters saw themselves as benevolent providers to the slave populations; however, their violent and harsh use of punishment caused much discontent in the slave population. Moreover, slaves resented the fact that they had little control over their lives because it was their masters who decided who should marry who and the masters even had power to break families by selling the slave children in auction blocks. The continual misappropriation of human rights prompted egalitarian thinking amongst white Americans and gradual laws to abolish slavery were passed. During the American Revolution many slaves were set free in the South and many more ran away from their masters. The antislavery movement during the revolution and after achieved emancipation of slaves in the North but no impact on slavery in the South.
During the Antebellum era cotton kingdoms were founded and huge numbers of slaves worked in the cotton plantations in the South. Slavery had a new economic purpose, not only was slavery essential to the growth of the US economy by exporting cash crops and cotton, it was also central to the whole agricultural environment of the United States.

Slave owners mostly left the day to day supervision of slaves to overseers who treated the African slaves like animals. Although slave owners took care of their slaves by providing adequate food and clothing, most civil liberties were not available to slaves. The mistreatment of slaves and the repression of civil liberties sparked fierce debates between the North and the South. The North advocated abolition of slavery in the whole of United States but the South with considerable investment in slaves saw this social movement as uneconomical. The debate became more intense when Dred Scott was granted freedom under the Missouri compromise but later declared as property in the Supreme Court in 1857.
While the North was transformed by the industrial revolution, the South enjoyed an expansive cotton export trade. The era however, was about equality and liberty and the slave South was looked upon as backwards in a social sense. Politically, the South claimed that slavery was the backbone of its society and a practical necessity, this view was contested heavily by the North.

The slavery debate eventually transformed into civil war and during this war many black slaves ran away from their masters to areas under federal control. Also during this war many people in the South began to think on an egalitarian basis. After the confederates lost the war, Abraham Lincoln made the historic proclamation of emancipation which essentially freed all African slaves in the United States.