U.S ports are significant to the U.S. economy, handling more than 2 billion tons of domestic and import/export cargo annually. Since Sept. 11, 2001, much of the national focus on ports' preparedness has been on preventing potential acts of terror, the 2005 hurricane season renewed focus on how to protect ports from a diversity of threats, including natural disasters. This report was prepared under the authority of the Comptroller General to examine (1) challenges port authorities have experienced as a result of recent natural disasters, (2) efforts under way to address these challenges, and (3) the manner in which port authorities plan for natural disasters. GAO reviewed documents and interviewed various port stakeholders from 17 major U.S. ports.