People in Louisiana who visited Pornhub in recent months were met with a surprising new demand. Before they could stream sexually explicit videos, they had to provide proof that they were at least 18.

That’s because Louisiana lawmakers had passed legislation in 2002 requiring publishers of online material that could be “harmful to minors” to verify that their users were adults.

Louisiana is at the forefront of a sweeping national push to insulate young people from potentially harmful content by requiring certain online services to bar or limit minors on their platforms. As a result, people in many other states might soon find that they, too, need to use credentials such as digitized driver’s licenses to access a host of services, including popular social media apps.

The proposed restrictions, introduced by at least two dozen states over the past year, could alter not only the online experiences of children and adolescents. They could also remake the internet for millions of adults, ushering in a tectonic cultural shift to a stricter, age-gated online world.

The spate of new bills might come as a relief to parents who worry that their children are being bombarded by sexualized images or targeted by strangers online. But civil liberties groups say certain bills could make it difficult for Americans, including minors, to view online information they have a constitutional right to see, violating free speech principles.

Utah and Arkansas recently enacted laws that would require social apps including TikTok and Instagram to verify their users’ ages and obtain parental consent before granting accounts to minors. While many sites already ask people signing up for accounts for their birth dates — a self-reporting system that children can often subvert by entering a fake birth year — the new state rules could prompt many platforms to institute more stringent age-verification systems involving government IDs.

In late April four U.S. senators including U.S. Sen. Brian Schatz of Hawaii introduced the “Protecting Kids on Social Media Act.” The bill would require social networks to verify users’ ages, bar children younger than 13 and obtain parental consent for users who are 13 to 17.

Laurie Schlegel, the Republican state representative who spearheaded the Louisiana law, said she was inspired to act in 2022 after hearing a podcast in which singer-­songwriter Billie Eilish told Howard Stern that watching online porn as a child had “destroyed my brain.”

Schlegel said she believed the digital world needed the same kind of adult zones that exist in the physical world, where consumers are often asked to show a government ID before they can buy alcohol. As an example, she noted that Louisiana required online gambling and alcohol delivery services to verify patrons’ ages through credentials such as drivers’ licenses.

“We have agreed as a society not to let a 15-year-old go to a bar or a strip club,” Schlegel said. “The same protections should be in place online so that you know a 10-year-old is not looking at hard-core pornography.”

Civil liberties experts said some of the proposed restrictions on harmful material and social media sites could create age-verification barriers for Americans seeking to freely access online information. If the rules were not overturned, these experts argue, they could radically alter the internet — by changing the online world into a patchwork of walled-off fiefdoms or causing popular platforms to narrow their offerings to avoid triggering the rules.

“It could jam up free speech not only for minors,” but cut off access to online information for adults, said Nadine Strossen, a former national president of the American Civil Liberties Union.

Civil liberties groups said they were considering litigation to try to halt certain new laws.

Since Louisiana enacted its measure, at least a dozen other states have introduced similar age-verification bills for viewing online porn. Among them is Utah, which also has a digital driver’s license program. Many other states are pilot-testing mobile licenses.

Even so, there are loopholes. To get around the age checks, for instance, people in Louisiana might use location-­masking software, which can make them appear to be in another state.

But many sexually explicit sites have not yet set up age-verification systems for Louisiana users, said Solomon Friedman, a partner at Ethical Capital Partners, a private equity firm that recently acquired MindGeek, the company behind adult sites including Pornhub.

“Pornhub is fully complying with the law,” Friedman said, “notwithstanding the fact that we know that it doesn’t actually protect children because many other sites are not complying with it.”

To encourage greater compliance, Schlegel recently introduced a bill that would allow the state to impose specific monetary penalties for pornography sites that failed to verify users’ ages.

Some social media platforms said they were intensifying their drive to identify and remove underage users.

Meta said it had started using artificial intelligence tools to help identify young people who misrepresent their age on Instagram and Facebook Dating. TikTok, which uses a variety of methods to identify underage users, has said it removed more than 75 million accounts in 2022 that appeared to belong to children younger than 13.