Gahanna Plantation was founded by John Clark of Ross County, Ohio as an 800 acre (3.2 km²) farm. Its population grew over time, and it was incorporated in 1881. The first mayor of Gahanna was L. John Neiswander. According to the Gahanna Historical Society, the community was not named for the Biblical Gehenna, but from a local Native American word describing the meeting of three creeks, as the community is located at the confluence of branches of Big Walnut Creek, once called Gahanna Creek. Gahanna is also known as a Bedroom community with most residents living in Gahanna and traveling to neighboring Columbus or other suburbs of Columbus to work.
In recent years, Gahanna has worked hard at revitalizing the downtown "Olde Gahanna" section of the city. In October 2004 Gahanna's new Creekside Project redevelopment and park extension began, making way for everything from public spaces and restaurants to residences and office space. It will also include a 389 space public parking garage, something sorely needed in an area with little space to park and explore Olde Gahanna. The multi-million dollar project is expected to bring in up to 150 new residents as well as bolster tourism to the area.