Utah has become the first US state to require social media firms get parental consent for children to use their apps and verify users are at least 18.
The governor says he signed the two sweeping measures to protect young people in the state.
The bills will give parents full access to their children's online accounts, including posts and private messages.
The move comes amidst heightened concern over the impact of social media on children's mental health.
The bills also impose a social media curfew that blocks children's access between 22:30 and 06:30, unless adjusted by their parents.