coal

In economics, the word externality refers to costs or benefits of a good or service not reflected in its price. For example, making gasoline requires petroleum extraction, transportation, and refinement; driving creates pollution, noise and congestion.  These in turn cause health and environmental damage.

Mountaintop mining is a widespread practice in eastern Kentucky, West Virginia and southwestern Virginia. It involves removing forests, clearing topsoil and using explosives to expose buried coal. Excess rock is pushed into nearby valleys, disturbing habitats and blocking streams.