From Wikipedia: The Great Exhibition of the Works of Industry of All Nations or The Great Exhibition, sometimes referred to as the Crystal Palace Exhibition in reference to the temporary structure in which it was held, was an international exhibition that took place in Hyde Park, London, from 1 May to 15 October 1851.
Excellent web sites:
From Wikipedia: The Exposition Universelle of 1855 was an International Exhibition held on the Champs-Élysées in Paris from 15 May to 15 November 1855. Its full official title was the Exposition Universelle des produits de l'Agriculture, de l'Industrie et des Beaux-Arts de Paris 1855.
From Wikipedia: The International Exposition of 1867 was the second world's fair to be held in Paris, from 1 April to 3 November 1867. Forty two nations were represented at the fair. Following a decree of Emperor Napoleon III, the exposition was prepared as early as 1864, in the midst of the renovation of Paris, marking the culmination of the Second French Empire.
From Wikipedia: Weltausstellung 1873 Wien (English: World Exposition 1873 Vienna) was the large world exposition that was held in 1873 in the Austria-Hungarian capital of Vienna. Its motto was Kultur und Erziehung (English: Culture and Education).
From Wikipedia: The 1884 World's Fair was held in New Orleans, Louisiana, United States. At a time when nearly one third of all cotton produced in the United States was handled in New Orleans and the city was home to the Cotton Exchange, the idea for the fair was first advanced by the Cotton Planters Association. The name World Cotton Centennial referred to the earliest-surviving record of export of a shipment of cotton from the U.S. to England in 1784. It was also known as the World's Industrial and Cotton Centennial Exposition.
From Wikipedia: The 1888 Barcelona Universal Exposition (in Catalan: Exposició Universal de Barcelona and Exposición Universal de Barcelona in Spanish) was Spain's first International World's Fair and ran from 20 May to 9 December 1888.
From Wikipedia: The Exposition Universelle of 1889 was a world's fair held in Paris, France, from 6 May to 31 October 1889.
From Wikipedia: The Trans-Mississippi and International Exposition was a world's fair held in Omaha, Nebraska from June 1 to November 1 of 1898. Its goal was to showcase the development of the entire West, stretching from the Mississippi River to the Pacific Coast. The Indian Congress was held concurrently.
From Wikipedia: The World's Columbian Exposition (the official shortened name for the World's Fair: Columbian Exposition also known as the Chicago World's Fair and Chicago Columbian Exposition) was a world's fair held in Chicago in 1893 to celebrate the 400th anniversary of Christopher Columbus's arrival in the New World in 1492.
The Woman's Building (Chicago) on Wikipedia
The World's Columbian Exposition of 1893 from the Illinois State Museum
From Wikipedia: The Exposition Universelle of 1900 was a world's fair held in Paris, France, from 14 April to 12 November 1900, to celebrate the achievements of the past century and to accelerate development into the next. The style that was universally present in the Exposition was Art Nouveau.
From Wikipedia: The Pan-American Exposition was a World's Fair held in Buffalo, New York from May 1 through Nov. 2, 1901.
Doin' the Pan. Website with tours of all the buildings, documents, and more.
Official Catalogue and Guide Book to the Pan-American Exposition (full e-book)
Pan-American Exposition of 1901 (includes films)
From Wikipedia: The Louisiana Purchase Exposition, informally known as the St. Louis World's Fair, was an international exposition held in St. Louis, Missouri from April 30 to December 1, 1904.
The Lewis and Clark Centennial Exposition, officially known as the Lewis and Clark Centennial and American Pacific Exposition and Oriental Fair, was a worldwide exposition held in Portland, Oregon, United States in 1905 to celebrate the centennial of the Lewis and Clark Expedition.
From Wikipedia: The Exposition Universelle et Internationale was a World's Fair held in Ghent, Belgium from April 26 to November 3, 1913 . Sometimes called the Ghent World's Fair.
From Wikipedia: The Panama–Pacific International Exposition (PPIE) was a world's fair held in San Francisco, California, U.S., from February 20 to December 4, 1915. Its stated purpose was to celebrate the completion of the Panama Canal, but it was widely seen in the city as an opportunity to showcase its recovery from the 1906 earthquake.
From Wikipedia: The 1929 Barcelona International Exposition (also 1929 Barcelona Universal Exposition, or Expo 1929 was the second World Fair to be held in Barcelona, the first one being in 1888. It took place from May 20, 1929 to January 15, 1930.
From Wikipedia: The Paris Colonial Exhibition (or "Exposition coloniale internationale", International Colonial Exhibition) was a six-month colonial exhibition held in Paris, France in 1931 that attempted to display the diverse cultures and immense resources of France's colonial possessions.
From Wikipedia: The Exposition Internationale des Arts et Techniques dans la Vie Moderne (International Exposition of Art and Technology in Modern Life) was held from 25 May to 25 November 1937 in Paris, France.
From Wikipedia: The 1939–40 New York World's Fair, which covered the 1,216 acres of Flushing Meadows-Corona Park was the second most expensive American world's fair of all time, exceeded only by St. Louis's Louisiana Purchase Exposition of 1904. Many countries around the world participated in it, and over 44 million people attended its exhibits in two seasons.
From Wikipedia: The Exposition internationale du bicentenaire de Port-au-Prince was a world's fair held in Port-au-Prince, Haiti in 1949 to mark 200 years since Port-au-Prince's foundation.