Learn how hydrofracking works and explores the controversy surrounding its potentially harmful impact on the environment.Even before the first glorious ring of the Liberty Bell, America was a land of freedom and promise. The Cornerstones of Freedom series explores what inspires people from all over the world to start life anew here, endure the economic and social upheavals, and defend the land and rights that are unique to the United States of America. Despite a growing interest in renewable energy sources, most of the energy used in the United States still comes from fossil fuels. At the same time, many Americans would like to decrease the country''s dependence on foreign oil and gas supplies. Hydraulic fracturing, or "hydrofracking," is one possible solution to meeting the nation''s natural gas needs.