Buffalo County is a county in the U.S. state of Nebraska. As of the 2010 census, the population was 46,102, making it Nebraska's fifth-most populous county. Its county seat is Kearney. The county was created in 1855 and later organized in 1870. It was named after the then-prevalent buffalo herds. Buffalo County is part of the Kearney, NE Micropolitan Statistical Area. In the Nebraska license plate system, Buffalo County is represented by the prefix 9; when the license plate system was established in 1922, the county ranked ninth in number of registered vehicles.