Westerville is a city in Franklin and Delaware counties in the U.S. state of Ohio. A northeastern suburb of Columbus, the population was 36,120 at the 2010 census. Westerville is the home of Otterbein University. Westerville was once known as "The Dry Capital of the World" for its strict laws prohibiting sales of alcohol and for being the home of the Anti-Saloon League, one of the driving forces behind Prohibition at the beginning of the 20th century.