More than 90,000 California public school students are autistic, a number that has risen more than six-fold since 2001, according to the latest data from the California Department of Education.
The figure represent a jump of about 6,000, or 7 percent, from 2013-14 to 2014-15. More than one of every 75 kindergartners in California public schools is classified as autistic.
The number of autistic students statewide has risen by between 5,000 and 7,000 every year for a decade. In 2001, there were about 14,000 autistic students in the state.
Each year since at least 2001, the number of autistic students has risen by 7 percent or more, state figures show.
In Sacramento County, the number of autistic students rose by about 340, or 11 percent, to roughly 3,400 from 2013-14 to 2014-15. The number of autistic children also rose in El Dorado, Placer and Yolo County.
Theories for the rise, which is a nationwide phenomenon, include improved autism screening, broader definitions of the condition and a genuine increase in autism cases.
A University of California study concluded that changes in diagnoses patterns alone cannot explain the rise in the disease. Instead, the study postulated that environmental factors were partially to blame and called for more study of the effects of viruses, pesticides, chemicals and other substances on the development of autism.
Fears that modern vaccines cause autism have led some parents to forego vaccinating their children. The American Academy of Pediatrics says no evidence exists linking autism to vaccines. A new state law that will take full effect in July will eliminate "personal belief exemptions" allowing parents to opt their children out of vaccinations.
This chart shows the number of students with autism statewide since 2000.