The Louisiana Purchase Exposition, of "Meet Me In St. Louis" fame, opened on April 30, 1904. (It had originally been scheduled for 1903, but delays caused the opening to be pushed back.) By the time the fair closed at the beginning of December, 1904, some 20 million people had visited the site, which covered 1275 acres and boasted 1500 buildings. This image was taken at the opening day ceremonies in front of the Louisiana Purchase Monument. The crowd is listening to a speech by David Rowland Francis, the President of the Exposition. After all the opening speeches and ceremonies, President Theodore Roosevelt, back in Washington D.C., touched a telegraph key which put in motion all of the engines of the Exposition.

From Louisiana and the Fair, Volume 4