Racist text messages invoking slavery raised alarm across the country this week after they were sent to Black men, women and students, including middle schoolers, prompting inquiries by the FBI and other agencies. The messages, sent anonymously, were reported in several states, including New York, Alabama, California, Ohio, Pennsylvania and Tennessee. They generally used a similar tone but varied in wording. Some instructed the recipient to show up at an address at a particular time “with...