Glens Falls is a city in Warren County, New York, United States and is the central city of the Glens Falls Metropolitan Statistical Area. The popul…Glens Falls is a city in Warren County, New York, United States and is the central city of the Glens Falls Metropolitan Statistical Area. The population was 14,830 at the 2020 census. The name was given by Colonel Johannes Glen, the falls referring to a large waterfall in the Hudson River at the southern end of the city.