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.
Actually only the Gemini Titan II and the Mercury Atlas remain. They were refurbished and rededicated in 2004. The Saturn V "boat tail" remained for many years, but did not survive the test of time and many years of bird's nests! The Mercury Capsule that was mounted atop the Atlas for many years was replaced with a replica, and the original is now on display inside the Hall of Science since it is indeed an actual flown capsule from an early unmanned test.