Generally speaking, It is not illegal in the US unless you leave visible marks (e.g. bruises). Even then, it would be reported but little action would be taken unless there are additional issues with the child’s safety.
It is still common in many places for a “whooping” to be used to keep kids in line.
I do not support criminal prosecution for parental spanking but I consider you've already failed as a parent if you need to "whoop" a child. In another world where child welfare services have a better reputation, I might even suggest that such parents should be forcefully relieved from parental duties.
It is still common in many places for a “whooping” to be used to keep kids in line.