According to Professor Samuel Williams of Harvard College, the Darkness was seen at least as far north as Portland, Maine, and extended southwards to New Jersey. The Darkness was not witnessed in Pennsylvania.
The earliest report of the darkness came from Rupert, New York, where the Sun was already obscured at sunrise.
Professor Samuel Williams observed from Cambridge that: "This extraordinary darkness came on between the hours of 10 and 11 A. M. and continued till the middle of the next night."
Reverend Ebenezer Parkham, of Westborough, Massachusetts, reported peak obscurity to occur "by 12", but did not record the time when the obscuration first arrived.
At Harvard College, the obscuration was reported to arrive at 10:30 AM, peaking at 12:45 PM, and abating by 1:10 PM, although a heavy overcast remained for the rest of the day.
The obscuration was reported to have reached Barnstable, Massachusetts, by 2:00 PM, with peak obscurity reported to have occurred at 5:30 PM.
For several days before the Dark Day, the Sun as viewed from New England appeared to be red, and the sky appeared yellow. While the Darkness was present, soot was observed to be collected in rivers and in rain water, suggesting the presence of smoke. Also, when the night really came in, observers saw the moon as red as blood. For portions of New England, the morning of 19 May 1780 was characterised by rain, indicating that cloud cover was present.
Since communications technology of the day was very primitive, most people found the darkness to be baffling and inexplicable. Since science could not explain it, they applied religious interpretations to the event. The Dark Day of 1780 was, and still is, regarded by many as a supernatural event caused by God.
I choose, for one, to meet Him face to face, No faithless servant frightened from my task, But ready when the Lord of the harvest calls; And therefore, with all reverence, I would say, Let God do His work, we will see to ours. Bring in the candles.
Today, some Christians, especially those among Seventh-day Adventists citing extracts of Biblically sequential events, "... the sun be darkened, the moon shall not give her light, and the stars shall fall from heaven... " (Matthew 24:29 (NKJ) re signs preceeding the return of Christ) and interpretations of the event as cited by Ellen G. White, believe that the Dark Day was a fulfillment of Biblical and end-times prophecy. Also see Revelation 6:12 "... and behold, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became like blood. 13 And the stars of heaven fell to the earth, as a fig tree drops its late figs when it is shaken by a mighty wind." (NKJ)
Although supernatural in nature according to those who witnessed the event, it may well have been 'natural' causes used in the context of a seemingly supernatural sequence of events.