While patterns are found, the mystery of why autism occurs remains a mystery.
The clusters, says the research, are mainly in affluent areas where the demographic consists of a high concentration of mostly white, educated parents.
It's all part of an ongoing investigation to find out why cases of autism appear to centralize in certain locations and not in others. Researchers at the University of California Davis, who conducted the study, were hoping to uncover the reason for the uptick in autism, which affects 1 in 110 children.
"We already know that people with a higher education in the United States are more likely to get a diagnosis of autism for their child. It doesn't necessarily mean that autism occurs more frequently in those families," said a spokesman for the study.