Buffalo is a city in the U.S. state of New York and the county 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 Canada–United States border. With a population of 278,349 according to the 2020 census, Buffalo is the second-most populous city in New York state and the 81st-most populous city in the U.S. Buffalo and the city of Niagara Falls together make up the two-county Buffalo–Niagara Falls metropolitan area, which had an estimated population of 1.2 million in 2020, making it the 49th-largest metro area in the U.S.