Gardner is a city in Johnson County, Kansas, United States. As of the 2010 census, the city population was 19,123.
Gardner was founded where the California Trail and Santa Fe Trail divided, sending travelers due west over the mountains and through Colorado and Salt Lake City toward San Francisco or through Sante Fe and Albuquerque toward Los Angeles and San Diego.
Gardner was founded as a Free-Stater settlement in 1857. Settled primarily by emigrants from Massachusetts, it may have been named for Henry Gardner, then governor of Massachusetts. Four years after its establishment, it became the first community in Johnson County — and perhaps the first in the state — to experience an attack by Confederate forces.