California may be home to artificial intelligence, self-driving cars and some of the world’s biggest technology companies, but when it comes to violence against women, researchers say the clock appears to have stopped nearly 20 years ago.

A sweeping new study by researchers at the University of California, Berkeley School of Public Health has found that rates of violence against women in the state remained largely unchanged between 2005 and 2022, exposing what experts describe as deep-rooted racial and social inequalities hidden beneath official crime narratives.

The research, published in the American Journal of Preventive Medicine, analyses more than 763,000 assault-related injuries and deaths involving women across California. What emerged was a disturbing pattern. Black women, despite making up only 6.5% of the state’s female population, accounted for nearly 22% of all assault injuries serious enough to lead to hospitalisation or death.

Across all age groups, Black women suffered assault-injury rates 3.8 times higher than white women.

Inside emergency wards, doctors and nurses continued to see the same wounds year after year. Bruises. Broken bones. Knife injuries. Trauma cases arriving in the middle of the night. The study suggests those hospital beds may reveal a far harsher reality than police files alone.

“We have these persistent racial disparities that just haven’t changed over time,” said Emily Liu, lead author of the study and a PhD candidate at UC Berkeley. “And in general among women, violence has stayed pretty stable across time, which says that we’re not paying enough attention to systemic issues driving these trends.”

Researchers said one major problem lies in how violence data is recorded. Police reports often rely on an officer’s perception of a victim’s race or ethnicity, while hospital records usually depend on information directly reported by patients themselves. That difference matters.

According to the study, Indigenous and multiracial women are frequently omitted from police-based analyses or grouped into vague categories, such as "others," effectively making many victims statistically invisible.

The findings also revealed an unexpected age shift in vulnerability. Black women under 65 faced the highest risks of violence for much of adult life. But after 65, multiracial women became the group at greatest risk, showing how patterns of danger evolve with ageing.

Researchers cannot separate the violence from California's social history.

“Community violence is a product of structural racism,” Liu said. In simple terms, structural racism refers to longstanding systems that leave certain communities with poorer housing, weaker schools, fewer health services and less economic investment over generations.

The study points to practices like redlining—a decades-old policy where minority neighbourhoods were denied loans and investments— as part of the deeper roots of today’s violence. Streets neglected half a century ago are often the same communities that are still struggling with poverty, instability, and higher injury rates today.

Jennifer Ahern, a professor of epidemiology and senior author of the research, said some local programs are making progress, but broader change remains painfully slow.

“I think there is hope in the sense that there are people really engaged in trying to come up with creative solutions to these problems,” Ahern said. “But like many social problems, they’re just very entrenched.”

The findings add to a growing body of work from Liu and Ahern, examining hidden health inequalities in California. In earlier research published last year, the team reported that nearly 73% of adolescents treated for self-harm injuries between 2005 and 2021 were girls. Reports involving multiracial teenage girls rose by around 75% after 2016.

Researchers believe hospital-based data may offer one of the clearest pictures yet of who is suffering—and who is overlooked.

For many readers, the numbers raise an uncomfortable question. If violence levels have barely moved since the era of flip phones and dial-up internet, despite years of awareness campaigns and policy promises, has society mistaken activity for progress?

The study’s answer is difficult to ignore: communities cannot heal fully until the deeper fractures beneath them are repaired.