About 1 in 36 children in the United States are identified as being on the autism spectrum, based on the most recent data from the CDC’s monitoring network. Globally, the World Health Organization estimates that roughly 1 in 127 people worldwide had autism as of 2021. These numbers have climbed sharply over the past two decades, driven largely by broader diagnostic criteria, greater awareness, and improved screening, particularly among groups that were historically underidentified.
Prevalence in the United States
The CDC tracks autism prevalence through its Autism and Developmental Disabilities Monitoring (ADDM) Network, which reviews records of 8-year-olds at sites across the country. In the year 2000, the network reported a prevalence of about 1 in 150 children. By 2010, that figure had more than doubled to 1 in 68. The most recent surveillance data puts the number at approximately 1 in 36, meaning nearly 3% of children in the monitored age group have received an autism diagnosis.
Applied to the broader U.S. child population, that translates to well over 2 million school-age children. In the 2022-23 school year, autism accounted for 13% of all students receiving special education services under federal law, making it the fourth-largest disability category in public schools. That 13% share comes from a total of 7.5 million students with disabilities, putting the number of students served under the autism category at roughly 975,000.
How Many Adults Are on the Spectrum
Estimating the number of autistic adults is harder because large-scale tracking systems focus on children. Many adults grew up before modern screening practices existed and were either misdiagnosed or never evaluated at all. A large population-based study using primary care records in England found that between 59% and 72% of autistic people in the general population may be undiagnosed. If those proportions hold across countries, the actual number of autistic adults is significantly higher than official counts suggest.
Adults who were children in the 1990s would have fallen under a prevalence estimate closer to 1 in 150. Adults born in the 1970s and 1980s grew up under even narrower diagnostic definitions, when only the most visibly affected individuals were identified. Many of these people are now seeking evaluations in their 30s, 40s, and beyond, particularly women and people of color who were disproportionately missed during childhood.
Global Estimates
The WHO’s estimate of 1 in 127 people worldwide is an average, and actual reported rates vary enormously by country. Much of the variation comes down to access to diagnostic services rather than true differences in how common autism is. In many low- and middle-income countries, prevalence data simply doesn’t exist because the infrastructure for screening and diagnosis isn’t in place. Well-controlled studies in some countries have reported rates considerably higher than the global average, closer to what the U.S. and parts of Europe have documented.
Differences by Sex and Gender
Autism has long been described as roughly three to four times more common in boys than girls, but that gap is narrowing quickly. A 2025 study tracking the entire Swedish population over 35 years found that the male-to-female ratio for autism diagnoses by age 20 dropped from about 1.9 in 2016 to 1.2 in 2022. Among people diagnosed between 2020 and 2022 who were older than 15, the ratio was no longer skewed toward males at all. The researchers projected that the cumulative ratio could reach full parity by 2024.
Among younger children, around age 10, the ratio has remained relatively stable at about 3 boys for every girl. This suggests that girls and women are still being identified later in life rather than in early childhood, likely because screening tools were originally developed based on how autism presents in boys. As clinicians get better at recognizing the ways autism manifests in girls, the childhood gap is expected to continue closing.
Differences by Race and Ethnicity
For years, white children were diagnosed with autism at higher rates than children of other racial and ethnic backgrounds. That pattern has reversed. The most recent ADDM data from 2022 found that prevalence among white children (27.7 per 1,000) was actually the lowest of any racial or ethnic group. Asian or Pacific Islander children had the highest identified rate at 38.2 per 1,000, followed by Black children at 36.6, Hispanic children at 33.0, and multiracial children at 31.9.
This shift reflects improvements in outreach and screening in communities that were historically underserved, not a sudden change in who develops autism. The earlier gap was a gap in access to evaluation, not a gap in actual prevalence. As diagnostic access has expanded, the numbers have started to reflect what researchers long suspected: autism occurs at similar rates across racial and ethnic groups.
Why the Numbers Keep Rising
The most common question people have when they see these numbers is whether autism itself is becoming more common or whether we’re simply getting better at finding it. The answer is mostly the latter, though researchers haven’t entirely ruled out a modest true increase.
Several factors have driven the rise. The definition of autism expanded significantly in the 1990s and again in 2013, folding in what was previously called Asperger’s syndrome and other related conditions. Screening recommendations have broadened, with pediatricians now routinely checking for autism at 18- and 24-month well-child visits. Public awareness has increased dramatically, meaning parents and teachers are more likely to seek evaluation for children who show early signs. And as the data on race, ethnicity, and sex make clear, communities that were previously overlooked are now being identified at rates that better match reality.
The jump from 1 in 150 in 2000 to 1 in 36 today is striking, but it’s worth remembering that many of the people now counted were always autistic. They just didn’t have a diagnosis.