Ellsworth is a city in and the county seat of Ellsworth County, Kansas, United States. As of the 2020 census, the population of the city was …Ellsworth is a city in and the county seat of Ellsworth County, Kansas, United States. As of the 2020 census, the population of the city was 3,066. Known as a cow town in the 1870s, when the Kansas Pacific Railroad operated a stockyard here for shipping cattle to eastern markets, in the 21st century, it serves as the trading center of the rural county.