Nearly half a million miles of high-volume pipeline transport natural gas, oil, and other hazardous liquids across the United States. These transmission pipelines are integral to U.S. energy supply and have vital links to other critical infrastructure, such as power plants, airports, and military bases. While an efficient and fundamentally safe means of transport, many pipelines carry volatile, flammable, or toxic materials with the potential to cause public injury and environmental damage. The nation’s pipeline networks are also widespread, running alternately through remote and densely populated regions, some above ground, some below; consequently, these systems are vulnerable to accidents and terrorist attack. This book provides an overview of the federal pipeline safety program and the federal role in pipeline security, with a focus on the nation’s overall strategy to protect transportation infrastructure.