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.
Slaves for the Trans-Atlantic slave trade were initially sourced in Senegambia and the Windward Coast. Around 1650 the trade moved to west-central Africa (the Kingdom of the Kongo and neighboring Angola). The transport of slaves from Africa to the Americas forms the middle passage of the triangular trade.