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.
The IBM Selectric typewriter, introduced in 1961, was featured at the NYWF, and the IBM pavilion design was even reminiscent of the Selectric type ball. It turns out that the Soviets developed a series of sophisticated bugs that could be installed in US diplomat's Selectric typewriters, and radio out what was being typed, by monitoring the ball motion: http://arstechnica.com/security/2015/10/how-soviets-used-ibm-selectric-keyloggers-to-spy-on-us-diplomats/
I went with a dozen or so friends. I was 16 at the time .It was packed with people but, we didn`t notice or care. The following day was the one in which over 450,000 attended for the last day. I don`t know the attendance on the 16th .It was a Saturday .The major pavilions like G.M.,Ford , and G.E had long lines but, because that`s what we came to see my friends and I would wait no matter how long it took.The reason there were so many of us was because it was a camp reunion..
A bit of world's fair trivia: If one looks to the left of the photo of Buffalo there is a dark skyscraper with three lighter colored building just to the left. I believe the one in the middle of those three is the 1912 Niagara Mohawk Tower better known as the Electric Tower to residents of the city. It was built with the Pan American Exposition's Electric Tower in mind. There were efforts to preserve the original Electric Tower along with the Temple of Music when the Pan closed in November of 1901. Those efforts failed. https://en.wikipedia.org/wiki/Electric_Tower I hope this link takes you to the story of the Electric Tower, Buffalo's permanent reminder of its world's fair.