It was one of those days when everything happens. On the morning of Friday, June 19, 1936, more than 50,000 Black visitors descended on Fair Park, in Dallas. They came on chartered trains and buses for a special Juneteenth program at the Texas Centennial Exposition, a world’s fair that had opened that month, where they were treated to performances by Cab Calloway’s Cotton Club Orchestra, artworks by the famous painter Aaron Douglas, and speeches by Black dignitaries. And then, at 8 p.m.,