Lyon County is a county located in the U.S. state of Kansas. Its county seat and largest city is Emporia. As of the 2020 census, the county population was 32,179. The county was named for Nathaniel Lyon, a general who was killed at the Battle of Wilson's Creek during the American Civil War.

Emporia is a city in and the county seat of Lyon County, Kansas, United States. As of the 2020 census, the population of the city was 24,139. Emporia lies between Topeka and Wichita at the intersection of U.S. Route 50 with Interstates 335 and 35 on the Kansas Turnpike. Emporia is also a college town, home to Emporia State University and Flint Hills Technical College. It is home of two annual sporting events: Unbound Gravel and Dynamic Discs Open.