GAHANNA, Ohio – For the second year, Gahanna has taken the title for being the hottest zip code in the country for home sales. Realtor.com rolled out its top 10 hottest zip codes, which is topped by Gahanna’s main 43230 zip. Second place goes to the St. Louis suburb of Ballwin, Missouri. Even with mortgage rates hovering around 6.5% for the last year, it hasn’t slowed down the housing market in Gahanna.