evidence: How does the CDC arrive at this number? CDC researchers collect health and school records for 8-year-old children who live in select U.S. counties. These researchers are part of the Autism and Developmental Disabilities Monitoring Network, which the CDC set up in 2000 to estimate autism prevalence. [...] Autism prevalence has traditionally been highest in white children in the U.S, but this is starting to change. African-American and Hispanic children have lower rates of diagnosis because of a lack of access to services. Widespread screening has improved detection of autism in these groups, and raised overall prevalence.