Is it safe for young girls to run the 5K (3.1 mile) distance?

Children’s bodies are well suited for endurance exercise, and numerous studies have shown that children show many positive physiological adaptations to endurance exercise training. The keys are gradual progression and common-sense adult supervision. If those conditions are met, running 3 miles is a reasonable goal for most young people.
-Russell R. Pate, Ph.D., Department of Exercise Science, University of South Carolina