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.
Thus Canada was the closest place for slaves to escape. The Fugitive Slave Act and the Underground Railroad. In 1899, Harriet Tubman purchased a home in Auburn, New York. Tubman, after escaping slavery, lead, on 15 trips to the South, hundreds of Blacks to freedom, via The Underground Railroad, in the North and Canada.