It probably depends on how they are interviewing for OCI. If each office is interviewing separately, then you probably want to make sure to highlight one city specifically. If it's just one interviewer for the firm generally you can still designate a preference, but make it clear you're interested in the firm generally, regardless of city.
If the Web site lists Columbus, you should probably stick to Columbus. For whatever reason, Akron may not be hiring summer associates from your school or at all.