In its 2005 Archaeological Assessment of Washington Square Park [PDF download], the New York City Parks and Recreation Department confirms that corpses “possibly numbered as many as 20,000 and it appears these burials remain under varying depths of fill.” In the popular guidebook Inside the Apple: A Streetwise History of New York City by Michelle Nevius and James Nevius, the authors detail, “While estimates vary, it seems likely that over 20,000 people were buried in the land.... The bulk of the bodies were never disinterred, which means that they remain to this day under the grass and pavement of Washington Square.” So, how did those bodies get there? In 1797, the quickly expanding New York City government purchased a portion of an old farm for $4,500 to create a potter’s field—a burial ground for the indigent, poor, criminals, and victims of epidemic. The potter’s field operated for almost thirty years and occupied what is now the eastern two-thirds of Washington Square Park. It also happened to be adjacent to several established church cemeteries, adding to the area’s body count. In Around Washington Square Harris commented that this area was a “natural choice for such bleak facilities because it was a rural northern suburb of the city and already the site of cemeteries owned by downtown churches.” Hundreds of people who could not afford to be buried privately were laid to rest in the field. Soon, the city sheriff erected a public gallows, near the current location of the Square’s fountain. Three-quarters of a mile away was a prison on the Hudson,[Blackwell's Island Penitentiary] which Harris describes as “another source of supply for field and noose.” What ultimately put the burial ground over capacity were the series of epidemics of yellow fever which struck in the years 1797, 1798, 1801, and 1803. This caused the city to seek and create a new, larger potter’s field at the current site of Bryant Park. (The bodies in Bryant Park were however relocated to Ward’s Island, and may still be there...) excerpted from>>>> http://www.nypl.org/blog/2011/03/10/grim-origins-washington-square-park