The trade show aspect (incredible new steam engines! super-sized canteloupes!) was supplanted by industry-specific expositions. The aspect of displaying unusual foreign cultures and faraway lands came to seem exploitative, and didn’t interest nations who wanted to demonstrate how modern they were, not how colorful. In addition, it became possible for large numbers of people to simply visit other countries instead of viewing a reconstructed village.

The midways full of thrill rides were supplanted by theme parks such as Disney and Six Flags. Television reduced the curiosity-seeking value of static displays, and pavilions began to simply be theaters for viewing television programs.

Late-20th century expos, especially in North America, seemed dominated by corporate pavilions, which were of dubious marketing value to the companies and felt a little distasteful to attendees.

But, as noted, World’s Fairs are still held.

Morris Dickstein expands on theses theme in his essay “From the Thirties to the Sixties: The World’s Fair in its own Time,” published in Remembering the Future: The New York World’s Fair from 1939 to 1964.