The stark images reveal North America's iconic - and most powerful - waterfall to be almost as dry as a desert.
In June 1969, U.S. engineers diverted the flow of the Niagara River away from the American side of the falls for several months.
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Stark: A completely dry Niagara Falls has never been seen before or since the six months in July 1969 when U.S. engineers set about restructuring the American side of the twin landmark.
Mountain of rubble: This set of photos only recently came to light when Russ Glasson found them in a shoebox in his in-laws' Connecticut garage
Their plan was to remove the large amount of loose rock from the base of the waterfall, an idea which they eventually abandoned due to expense in November of that year.
During the interim, they studied the riverbed and mechanically bolted and strengthened a number of faults to delay the gradual erosion of the American Falls.
The team, made up of U.S. Army Corp of Engineers, blew up their temporary dam in November 1969 and six million cubic feet of water once again thundered over the falls' sides every minute.
Now, after lying unseen for more than four decades
Plan: The U.S. Army Corp of Engineers studied the riverbed and mechanically bolted and strengthened a number of faults to delay the gradual erosion of the American Falls
Historical moment: In order to stop the Niagara River running over the American Falls, engineers constructed a dam consisting of 27,800 tons of rock, stopping the water for the first time in 12,000 years
Russ Glasson recently stumbled across the pictures, which were taken by his in-laws, and had been left in an old shoebox in their garage for over four decades.
Mr Glasson said: 'My in-laws took these pictures during the six months through June to November that the Army was working to improve the health of the American Falls.'
Two rockslides from the plate of the falls in 1931 and 1954 had caused a large amount of rock to be collected at the base.
In 1965, reporters at local newspaper Niagara Falls Gazette revealed that the America Falls would eventually cease to flow and stop altogether if the rocks were not removed.
Four years later, the U.S. Army Corp of Engineers were charged with de-watering the falls to clean the river bed and to remove any loose rock at the bottom of the falls.
Gradual deterioration: Two rockslides from the plate of the falls in 1931 and 1954 had caused a large amount of rock to be collected at the base
Eerie calm: The temporary dam can be seen in the top-right of this photograph
Thunderous: The American Falls as they normally appear, with millions of gallons of water hurtling over the edge every minute
To achieve this the army had to build a 600ft dam across the Niagara River, which meant that 60,000 gallons of water that flowed ever second was diverted over the larger Horseshoe Falls which flow entirely on the Canadian side of the border.
The dam itself consisted of 27,800 tons of rock, and on June 12, 1969, after flowing continuously for over 12,000 years, the American Falls stopped.
Over the course of the next six months thousands of visitors flocked to the falls to witness the historic occasion.
Once the engineers had removed the collected rocks from the falls base and made geological testing to make safe the rest, the falls were re-watered on November 25 in front of 2,650 onlookers.
Tourist hotspot: The Maid Of The Mist cruise boat journeys near to the Canadian Falls. The American Falls can be seen in the distance on the left
Niagara Falls in 1869...!!
Niagara Falls in 1911...!!
Niagara Falls in 1985...!!
Niagara Falls in 1999...!!
Niagara Falls in 2005...!!
Ends Here With Such A Wonder Of The World.