School districts across the country are increasingly taking on social media, filing lawsuits that argue that Instagram, Snapchat, TikTok and YouTube have helped create the nation’s surging youth mental health crisis and should be held accountable.

The legal action started in January, with a suit by Seattle Public Schools, and picked up momentum in recent weeks as school districts in California, Pennsylvania, New Jersey and Florida have followed. Lawyers involved say many more are planned.

San Mateo County, home to 23 school districts and part of the Silicon Valley in northern California, filed a 107-page complaint in federal court last week, alleging that social media companies used advanced artificial intelligence and machine learning technology to create addictive platforms that cause young people harm.

“The results have been disastrous,” the filing asserts, saying more children than ever struggle with their mental health amid excessive use of the platforms. “There is simply no historic analog to the crisis the nation’s youth are now facing,” it said.

The suit points to recent data from the Centers for Disease Control and Prevention showing climbing rates of depressive symptoms and suicidal thoughts among the nation’s high school students. The increasing popularity of social media, it contends, “tracks precisely” with a youth mental health decline. It quotes President Biden’s remarks in his State of the Union address that tactics used by social media companies are an “experiment they are running on our children for profit.”

San Mateo County Superintendent of Schools Nancy Magee said in an interview that rampant social media use has left a mark on schools, to the point where administrators have observed a spike in mental health emergencies during the school day. There have been “very serious” cyberbullying incidents related to social media — with content “nearly impossible” to get the companies to take down — and school threats that have kept students at home, she said.