Many nations have organized emergency response systems to address natural, technological, and human-caused disasters. The United States of America has a multilevel approach that starts with the municipality, and includes the state and the federal government in delivering services and support, which might be a useful model for other federal nations. Emergency response in the United States is organized around layers of systems. The Incident Command System is the tactical system used in the field. The National Incident Management System is the overarching approach that covers preparedness, response, recovery, and mitigation. The National Response Framework defines the roles of federal resources and systems in disaster response. Fifteen Emergency Support Functions designate which federal agency will coordinate the role, and what resources may be available during a Presidentially declared major disaster. The new ESF #14 designates seven lifeline systems that have to be maintained regardless of the extent of the disaster. Transportation is both a lifeline function and a critical infrastructure element, and is ESF #1.