Portal:Philadelphia/Did you know?/May 2010
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![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/87/Memorial_Hall_Phila.jpg/100px-Memorial_Hall_Phila.jpg)
… that the Centennial International Exhibition of 1876, the first world's fair in the United States, attracted about 10 million visitors, equivalent to about 20% of the nation's population at the time?