Although it lasted only for six months, Niagara Falls stopped after flowing continuously for over 12,000 years. It happened in June 1969 when U.S. Army Corp of Engineers was improving the health of the American Falls by diverting the 60,000 gallons flow of the Niagara River away to the Canadian side of the border. They built a 600ft dam across the river and removed a big amount of rocks from the falls base. American engineers also made geological testing to assure that all other stones were safe.
Niagara Falls was finally re-watered on November 25, 1969 when engineers blew up their dam. Over 2,500 onlookers were witnessing this historic occasion.
You can also see amazing images of the eerie calm at the falls shared by Russ Glasson from Connecticut and video after the jump.