Non-renewable resources are resources for which there is a limited supply. The supply comes from the Earth itself and, as it typically takes millions of years to develop, is finite. Non-renewable resources can generally be separated into two main categories; fossil fuels and nuclear fuels.
But there were pockets of the North on the eve of the Revolution where slaves played key roles in the economic and social order: New York City and northern New Jersey, rural Pennsylvania, and the shipping towns of Connecticut and Rhode Island.
Slightly more slaves came from the Nigerian coast than from Angola in the eighteenth century, while in the nineteenth century perhaps 30 percent of all slaves sent across the Atlantic came from Nigeria. Over the period of the whole trade, more than 3.5 million slaves were shipped from Nigeria to the Americas. Most of these slaves were Igbo and Yoruba, with significant concentrations of Hausa, Ibibio, and other ethnic groups. In the eighteenth century, two polities--Oyo and the Aro confederacy--were responsible for most of the slaves exported from Nigeria.