Bear in mind that there were no telephones; there was no radio or television; there was no telegraph. People often lived far away from their nearest neighbor. They knew little of what, at a given moment, was happening outside the patch of land where they resided.
The one thing a person could always count on -- that the sun would come up in the morning and stay up until evening -- suddenly could not be counted on at (http://www.cnn.com/2013/05/19/opinion/greene-day-of-darkness)
Since communications technology of the day was primitive, most people found the darkness to be baffling and inexplicable. Many applied religious interpretations to the event. . . .
Today, some Christians, especially those among Seventh-day Adventists citing extracts of Biblically sequential events, "... the sun will be darkened, the moon will not give its light, the stars will fall from the sky..." (Matthew 24:29 (WEB) are signs preceding 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 6:12–13 "... and there was a great earthquake. The sun became black as sackcloth made of hair, and the whole moon became as blood. The stars of the sky fell to the earth, like a fig tree dropping its unripe figs when it is shaken by a great wind." One prominent Seventh-Day Adventist, Arthur Maxwell, even mentions this event in his The Bible Story series (Vol. 10). Some Progressive Adventist scholars do not interpret this as a sign of Jesus' soon return. Traditional Historic and Conservative Adventists, who hold Ellen White's writings in higher regard, still consider this date as one of the fulfillments of biblical prophecy.
9. Bible Universe. Retrieved from http://www.bibleuniverse.com/prophecy/sun_darkness.asp.
10. The Dark Day. Retrieved from http://www.bibleprophecytruth.com/JesusChrist/thedarkday.asp.
11. Graeme Bradford, "Ellen White and the end times", chapter 17 in his More Than a Prophet. Berrien Springs, Michigan: Biblical Perspectives, 2006, p139
12. White, Ellen G. Maranatha. Napa, Idaho: Pacific Press Publishing Association, p. 150
In about 1886 a former slave named Harriet Powers crafted a quilt with one of its panels dedicated to New England’s Dark Day, ... (http://web.massar.oorg/may-19-1780-new-englands-dark-day)
Cause (A Theory): The likely cause of the Dark Day was smoke from massive forest fires. When a fire does not kill a tree and the tree later grows, scar marks are left in the growth rings. This makes it possible to approximate the date of a past fire. Researchers examining the scar damage in Ontario, Canada, attribute the Dark Day to a large fire in the area that is today occupied by Algonquin Provincial Park. (Ref. 13, 14 - http://en.wikipedia.org/wiki/New_England%27s_Dark_Day)
A supernatural phenomenon!?! Or a major forest fire happening hundreds of miles away?