New England's Dark Day refers to an unusual meteorological phenomenon that occurred on May 19, 1780, when an unexplained darkness enveloped parts of New England for several hours during the daytime. This event bewildered residents and prompted various supernatural explanations, with some attributing it to a divine omen or celestial event. Later investigations pointed to the possibility of smoke from widespread forest fires as the cause. The event was widely documented in contemporary diaries and newspapers.