2020’s murder increase is ‘unprecedented.’ But is it a blip?

After police discovered Huong Nguyen’s body in a car trunk earlier this year in New Orleans East, suspicion fell on her brother.

After being spotted on a surveillance camera walking away from his sister’s car the night she disappeared, Hoa Nguyen has been charged and, if convicted, could spend the rest of his life in prison.

For all its singular tragedy, Ms. Nguyen’s death is part of a tide of gun violence rising from New Orleans to Lubbock, Texas. Coming off a record low in homicides in 2019, New Orleans...