Most scientists estimate that Niagara Falls has shifted backwards more than 7.1 miles in the years since its creation, and without human interference, they expect the erosion to continue into the future.

Niagara Falls hasn't "shrunk" in height, but it has been physically receding (moving upstream) for thousands of years due to erosion. Historically, the falls moved south toward Lake Erie at a rate of about 3 feet per year. However, since the 1950s, human engineering has drastically slowed this process. By diverting massive amounts of water for hydroelectric power (up to 50% of the river's flow at night) and installing underwater weirs to distribute the flow more evenly, the erosion rate has been reduced to about 1 foot every 10 years. In terms of the physical "crestline," the Horseshoe Falls have changed shape due to massive rockfalls, most notably in 1931 and 1954. If left entirely to nature, the falls would eventually erode all the way back to Lake Erie and disappear, but with 2026-era geological monitoring and "water-flow management," the falls are expected to stay in their current location for at least the next 10,000 to 15,000 years, effectively "freezing" one of the world's most iconic landmarks in its current majestic state for many generations to come.