The park has historically been the start or the end point for many political demonstrations. Although the park was known for its labor union rallies and for the large 1861 gathering in support of Union troops, it was actually named for its location at the "union" of Bloomingdale Road (now Broadway) and Eastern Post Road (now extinct) decades before these gatherings. In April 1861, soon after the fall of Fort Sumter, it was the site of a patriotic rally of perhaps a quarter of a million people that is thought to have been the largest public gathering in North America up to that time. In the summer of 1864 the north side of the square was the site of the Metropolitan Fair.