A special investigative report by Scripps Howard News Service digs into the troubled condition of the embankments that stem floodwaters around the nation.

America's neglected levees put millions in danger
• Levee gaps could swamp Smithsonian, National Mall
• Millions could face huge flood insurance bills from levee map
• Certifying a levee as safe is costly and difficult
• Law changes could mean billions in flood insurance costs