Nearly half a million miles of oil and natural gas transmission pipeline criss-cross the United States. While an efficient and fundamentally safe means of transport, many pipelines carry hazardous 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; consequently, these systems are vulnerable to accidents and terrorist attack. This book explores how the various elements of U.S. pipeline safety and security activity fit together in the nation’s overall strategy to protect transportation infrastructure.