The 1893 Columbian Exposition introduced the United States as an industrial power on the world's stage.  Americans flocked to Chicago to ride the world's first Ferris Wheel, to hear Frederick Jackson Turner lecture on his frontier thesis and, perhaps most of all, to see electric light for the first time. As the exposition opened on May 1, 1893, President Grover Cleveland illuminated the fairgrounds  with the push of a button. The light exposed a nation transformed, a rapidly-industrialization, newly-urban United States,  full of new innovations and inventions. University of Tennessee historian  Ernest Freeberg  explains how that era, the era of Thomas Edison, inspired the the world of today in his new book, "The Age of Edison: Electric Light and the Invention of Modern America."