Only a few states have legislated a specific age to leave a child home alone, Illinois, Georgia, Oregon, and Maryland.
Generally speaking, the child must be safe, must feel safe, and know how to take care of themselves in an emergency.
The only age suggestions I can find are no younger that a mature 12 year old. Personally, I would not leave a child younger than 15 at home alone. That is just me!
As you know children have a tendency to NOT think before they act!
If you want to make sure you are legally covered in your area, you can call the business office of the Child Welfare Department in your area and ask them!