Staged to celebrate the completion of the Panama Canal, and drawing over 19 million visitors in only nine months, the Pan-Pacific International Expo rose like a literal jewel from the ashes of San Francisco's 1906 Earthquake and Fire.
A Century of Progress International Exposition was held in Chicago, Illinois from 1933 to 1934 to celebrate the city's centennial. The theme of the fair was technological innovation. Its motto was "Science Finds, Industry Applies, Man Conforms".
The 1939-40 New York World's Fair, located on the current site of Flushing Meadows-Corona Park, was one of the largest world's fairs of all time. The fair ran for two seasons and over 44 million people attended.
The Golden Gate International Exposition was held in San Francisco, California to celebrate the opening of the San Francisco-Oakland Bay Bridge and the Golden Gate Bridge. The exposition's first season ran from February 18, 1939 through October 29, 1939 and its second season was from May 25, 1940 through September 29, 1940.
The 1964/1965 New York World’s Fair, located on the current site of Flushing Meadows-Corona Park. The fair ran for two seasons and took place without sanctioning from the Bureau of International Expositions.
Expo 67 was held in Montreal, Quebec, Canada from April 27 to October 29, 1967. It was considered to be the most successful World's Fair of the 20th century, with over 50 million visitors and 62 nations participating.
PS - I see my gamma is off; the cover appears too light to me here. Bill, if this image file is needed I have it saved, scanned and restored, as a HUGE tiff file from when I did the illustrations and color corrections for the National Building Museum catalog/architecture text Designing Tomorrow.
I believe it to be highly polished United States States Steel sheeting provided by one of its subsidiaries, such as the National Tube Company, which supplied the Helicline's steel tubes. The Trylon was supplied by the Elmira, N.Y. plant of the American Bridge Company. The Perisphere's 2050 tons of steel was fabricated at the Ambridge, Pennsylvania plant of the American Bridge Company. The underside surface shows well in this Kodachrome taken after 10 PM - when enlarged you can see how they are fixed: