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.
By 1680, there were some 7,000 African slaves in the American colonies, a number that ballooned to 700,000 by 1790, according to some estimates. Congress outlawed the importation of slaves to the United States as of 1808, but the practice continued. The U.S. Civil War (1861-1865) resulted in the emancipation of approximately 4 million slaves.