Worldwide, roughly 1 in 127 people had autism as of 2021, according to the World Health Organization. That translates to more than 60 million people globally. In the United States, the numbers are considerably higher: about 1 in 31 children and an estimated 2.21% of adults, which means millions of Americans are living with autism today.
Global Prevalence
The WHO’s 2021 estimate of 1 in 127 is a global average, and actual rates vary dramatically depending on the country and how actively it screens for autism. Nations with robust diagnostic infrastructure tend to report higher numbers, while countries with fewer resources for evaluation report lower ones. That doesn’t necessarily mean autism is less common in those places. It often means fewer people are being identified.
Autism Rates in the United States
The CDC tracks autism prevalence among 8-year-olds through its Autism and Developmental Disabilities Monitoring (ADDM) Network. The most recent data, from 2022, found an overall prevalence of 32.2 per 1,000 children, or about 1 in 31. That’s a 22% increase over the 1 in 36 figure reported just two years earlier for the 2020 data cycle. Rates varied widely by location, from as low as 1 in 103 in Laredo, Texas, to as high as 1 in 19 in parts of California.
Among adults, the picture is harder to pin down because large-scale screening is far less common. A CDC study using 2017 data estimated that 2.21% of U.S. adults have autism. The states with the largest estimated adult populations include California (roughly 702,000), Texas (about 450,000), New York (342,000), and Florida (329,000).
How the Numbers Have Changed Over Time
The rise in reported autism prevalence has been steep. When the ADDM Network began tracking in 2000, the rate was 1 in 150 among 8-year-olds. By 2020, it had climbed to 1 in 36. By 2022, it reached 1 in 31. That’s roughly a fivefold increase in just over two decades.
Most researchers attribute this growth primarily to broadened diagnostic criteria, greater awareness among parents and clinicians, and improved screening, rather than to a true spike in how many people are autistic. When diagnostic standards were updated from DSM-IV to DSM-5 in 2013, about 81% of children previously diagnosed under the older criteria still met the new definition. The shift initially narrowed the diagnostic pool slightly, but evolving clinical practices quickly adapted, and prevalence figures continued to climb. Communities that were historically underdiagnosed, particularly Black, Hispanic, and Asian children, have seen some of the fastest increases as screening access has improved.
The Gender Gap Is Narrowing
Autism has long been described as far more common in boys, with a frequently cited ratio of about 4 to 1. Recent data tells a more nuanced story. A large birth cohort study published in The BMJ found that the male-to-female ratio for cumulative autism diagnoses dropped to just 1.2 to 1 by age 20 in 2022. The researchers projected the ratio could reach parity by 2024.
The pattern is age-dependent. Among children under 10, boys are still diagnosed roughly three times as often as girls. But after age 15, the gap essentially disappears in recent data. This strongly suggests that girls and women have been systematically underdiagnosed for decades rather than being inherently less likely to be autistic.
Several factors contribute to the diagnostic imbalance. Girls tend to develop stronger social and communication skills early on, which can mask the traits clinicians look for. Many girls and women also “camouflage,” consciously mimicking peers’ social behavior to fit in. Diagnostic tools were historically developed and validated using predominantly male study samples, making them less sensitive to how autism presents in females. As awareness of these biases has grown, more girls and women are being identified, which is a major driver of the shrinking gap.
Why Prevalence Varies So Much by Location
The nearly sixfold difference between the lowest and highest U.S. sites (9.7 per 1,000 in Laredo versus 53.1 per 1,000 in California) reflects differences in access to evaluation, local screening practices, availability of specialists, and how thoroughly health and education records capture developmental concerns. Areas with more pediatric specialists and universal screening programs consistently report higher rates. This pattern holds internationally as well: the WHO notes that reported prevalence varies substantially across studies worldwide, largely driven by how and whether countries look for autism in the first place.
In other words, higher reported prevalence in a given area usually signals better detection, not a greater risk of autism. The true global figure is almost certainly higher than 1 in 127, with many autistic people, particularly adults, women, and those in lower-resource settings, remaining undiagnosed throughout their lives.