Buffalo is a city in and the county seat of Johnson County, Wyoming, United States. The population was 4,415 at the 2020 census, down from 4,585 at the 2010 census. The city had experienced an economic boom due to methane production from the Coal Bed Methane Extraction method used in the Powder River Basin and surrounding areas. With the decline of methane production, Buffalo's population has stabilized since the 2010 Census.