In America, most states have laws that restrict piercings to those aged 18 or over. It may be possible to be pierced with a parent's permission but that is dependent on the establishment and on the local and state laws.
Some states don't have any rules prohibiting a minor from being pierced. This includes Hawaii, Iowa, Maryland, Massachusetts, Nevada, New Mexico, Oregon, South Dakota, Vermont, Washington, West Virginia and Wisconsin. Maryland, Massachusetts, Nevada, New Mexico, and Oregon are the only states in America that also don't have any state laws against the tattooing of a minor without a guardian's permission.