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.
I suspect some of the trees date back to 1938 when they were transplanted, many from Westchester County, to Flushing Meadow. However, those trees would be mainly along what was the Mall in 1939 leading from the Theme Center to the Lagoon of Nations. This is documented in pre-Fair publications in the 1930s. The 1938 construction, 1941 demolition, 1963 construction and 1966 demolition in the transportation area (in the case of this thread) is likely a different story. Maybe some of the 1963 trees survive today (near what was Ford) as Bill believes, but the footprints of the pavilions for two different fairs would lead one to believe that there was either a great deal of transplantation of 25 year old trees or new, smaller trees were planted for the second fair while 1938 trees are few and far between today.
There are rumors that a few of the trees along the Fountains of the Fairs date back to the '39-40 edition.
There was a large one from '39-40 that got moved to the Queens Botanical Garden in 1963 and is said to still be there, at the entrance gate.