Clay Center is a city in and the county seat of Clay County, Kansas, United States. As of the 2010 census, the city population was 4,334.
Clay Center was first settled in 1862. It was named from its position near the geographical center of Clay County.
The first post office was established in Clay Center on July 3, 1862.
Clay Center was located on the Chicago, Rock Island and Pacific and Union Pacific Railroads.
Clay Center is located at 39°22′48″N 97°7′23″W (39.379920, -97.123168). According to the United States Census Bureau, the city has a total area of 3.08 square miles (7.98 km2), all of it land. Clay Center is unique, because it is the geographic midpoint between Los Angeles, California and New York City, the two largest American cities. Both cities are exactly 1,224 mi (1,970 km) from Clay Center.
The climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Clay Center has a humid subtropical climate, abbreviated "Cfa" on climate maps.
As of the census of 2010, there were 4,334 people, 1,920 households, and 1,172 families living in the city. The population density was 1,407.1 inhabitants per square mile (543.3/km2). There were 2,158 housing units at an average density of 700.6 per square mile (270.5/km2). The racial makeup of the city was 96.9% White, 0.5% African American, 0.6% Native American, 0.3% Asian, 0.4% from other races, and 1.3% from two or more races.