America had a real shortage of people to work the cotton fields. Native Americans were not as suitable for slaves because they kept dying and running off. It was found that imported African slaves were much more suitable. The Africans that survived the long journey from Africa were too exhausted, sick, demoralized and depressed to run away. Besides they had nowhere to run.
The demand for slave labor boomed. Rich English merchants such as George Hibbert, owner of the West India Dock Company, hired ship builders to construct specialized ships for transporting human cargo from West Africa. Africans could be efficiently stacked up like cordwood in the holds of slave ships. Cloth, sugar, rice and rum were traded in Africa for human property that was then auctioned in the slave markets in the Americas.
Rivalry and resentments between the manufacturing North and the cotton producing South became a problem. The South was rich in land, cotton and slaves but poor in money. The South had to borrow heavily from English and Northern bankers at high interest rates to keep the cotton plantations going.
The South became similar to a colony of the North. The South exported raw materials and imported finished products from the North and England. The North was able to put high tariffs on imported English goods in order to collect revenues and to make its own manufactured products more competitive.