For over a decade, San Joaquin and Alameda counties have had the highest rates of violent crimes involving guns among California’s 15 largest counties, according to a study.

The Public Policy Institute of California, in a research it published this week, said that nearly 40 percent of violent crimes from 2010 to 2022 in San Joaquin and Alameda counties involved firearms.

The study, based on data from the California Department of Justice’s Criminal Justice Statistics Center, revealed that in the same period, 90 percent of all homicides recorded in both counties involved guns.

In Contra Costa County and San Francisco, around 70 percent and 60 percent respectively of their homicide cases involved guns. In Santa Clara and San Mateo counties, 50 percent and 38 percent respectively of similar cases were also committed with firearms, the study found.

Half of robberies committed in Alameda County from 2010 to 2022 involved guns, according to the study.

A graphic shows the percentage of violent crimes involving firearms in the 15 largest counties of California. Guns were more likely to be used in the commission of robberies, homicides and aggravated assaults in San Joaquin and Alameda counties, according to the data. (Public Policy Institute of California)

The Public Policy Institute of California also noted that in the same period, 40 percent of San Joaquin County’s recorded aggravated assaults involved firearms, “which is notably higher than other large counties.”

Twenty-eight percent of Alameda County’s aggravated assaults and less than 15 percent of similar cases in San Mateo County also involved firearms, the study disclosed.

California has the strictest firearm laws among states in the U.S., with its Legislature proposing and approving multiple bills aimed at addressing the prevalence of guns. Violent crimes in the state, however, have been soaring since 2019, with over half of recent crime numbers involving firearms, the Public Policy Institute of California noted.

In June, Gov. Gavin Newsom proposed a constitutional amendment to enshrine gun safety measures nationally. His proposed 28th Amendment to the U.S. Constitution includes four gun safety measures that are already part of California law: universal background checks, raising the firearm purchase age to 21, instituting a firearm purchase waiting period and barring the civilian purchase of assault weapons.