How Lighthouses, Navigational Aids, and Harbors Transformed the Great Lakes and America. Deep in the heart of North America lies a vast inland sea. Even today it remains more of a wilderness than the Alaskan bush or arid Death Valley. Yet, that same sea has been integral to the economies of two great nations and the 85 million live on its margins. This illustrated lecture will discuss the controversies, individuals and the infrastructure that shaped the Great Lakes. Lighthouses, harbors, and charts built by the federal government transformed a region and impacted the world.