America’s Last Top Model
In 1943, the Army Corps of Engineers began construction on a scale model that could test flooding in all 1.25 million square miles of the Mississippi River. It would be a three-dimensional map of nearly half of the continental United States, rendered to a 1/2000 horizontal scale, spanning more than 200 acres. It was so big that the only way to see all of it as once was from a four-story observation tower. Ryan Kailath paid it a visit.