Niagara Falls was frozen in 1911 and 1932.
During an extended winter cold snap a hardened crust of ice can accumulate over parts of the falls (the American Falls in particular) creating an amazing, naturally-formed ice…
During occasional periods of prolonged cold weather falling water and spray from Niagara Falls may freeze into ice formations, and ice mounds or floes may form in the Niagara River (sometimes creating ice bridges that stretch across the width of the river), but only once in recorded history has freezing weather actually stopped water from flowing over the falls. This instance occurred in March 1848 when a preponderance of ice above the falls reduced the flow of water over the falls to a trickle, as reported in the Buffalo Express newspaper:
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