SPRINGFIELD, Ohio — This city is besieged by a lie. Mayor Rob Rue could not meet with me at his office because of a series of anonymous bomb threats that shut down schools, hospitals and the municipal center. One morning this week, I watched as eight police cars sped up to City Hall and officers rushed inside, investigating the latest threat; it turned out to be a false alarm, like all the others. So far.Amid a crisis that is fundamentally about Springfield’s racial and cultural diversity, an annual celebration of that diversity called CultureFest set for later this month had...