Smith County is a county located in the U.S. state of Kansas. Its county seat is Smith Center. As of the 2020 census, the population was 3,570. The county is named in memory of J. Nelson Smith, a major in the 2nd Colorado Cavalry, killed at the Battle of Westport on October 21, 1864. The geographic center of the contiguous United States is located within the county, near Lebanon.

Lebanon is a city in Smith County, Kansas, United States. As of the 2020 census, the population of the city was 178.