Little Falls is a city in Herkimer County, New York, United States. The population was 4,605 at the time of the 2020 census, which is the second-smallest city population in the state, ahead of only the city of Sherrill. The city is built on both sides of the Mohawk River, at a point at which rapids had impeded travel upriver. Transportation through the valley was improved by construction of the Erie Canal, completed in 1825 and connecting the Great Lakes with the Hudson River.