Buffalo is a city in the U.S. state of New York and the seat of Erie County. It lies in Western New York, at the eastern end of Lake Erie, at the head of the Niagara River, on the United States border with Canada. With a population of 278,349 according to the 2020 census, Buffalo is the 2nd-largest city in New York state and the 78th-largest city in the United States.