How Many People Have Autism? Key Statistics

According to the CDC’s most recent data, approximately 1 in 36 children in the United States has been identified with autism spectrum disorder (ASD). This represents a significant increase from earlier estimates and reflects both improved screening methods and broader diagnostic criteria.

Understanding autism prevalence helps families, educators, and policymakers allocate resources and plan support services. If your child has been diagnosed with autism, Treetop ABA Therapy provides evidence-based therapy across multiple states.

U.S. Autism Prevalence Over Time

The CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network has tracked autism prevalence among 8-year-olds for more than two decades. The trend shows a steady increase:

Year	Prevalence	Approximate Rate
2000	1 in 150	0.67%
2004	1 in 125	0.80%
2008	1 in 88	1.14%
2012	1 in 69	1.45%
2016	1 in 54	1.85%
2018	1 in 44	2.27%
2020	1 in 36	2.78%

Source: CDC ADDM Network surveillance data

How Many People Have Autism in the U.S.?

Based on the 1 in 36 prevalence rate and U.S. Census population data, an estimated 5.4 million adults and approximately 1 million children in the United States are on the autism spectrum. The total number of Americans with autism is estimated to exceed 6 million.

These numbers represent diagnosed and identified cases. Many adults, particularly women and people of color, remain undiagnosed due to historical biases in screening and referral patterns.

Autism Prevalence by Gender

Autism is diagnosed significantly more often in males than females:

• Boys are diagnosed at a rate of approximately 1 in 23.
• Girls are diagnosed at a rate of approximately 1 in 100.
• The male-to-female ratio is roughly 3.8 to 1, according to CDC data.

However, researchers increasingly recognize that autism in girls and women is underdiagnosed. Females may present differently, often developing stronger social masking abilities that can delay or prevent diagnosis.

Autism Prevalence by Race and Ethnicity

The CDC’s data shows that autism prevalence is now similar across racial and ethnic groups, a change from earlier years when white children were diagnosed at higher rates. This shift reflects improvements in screening access and awareness across communities.

According to the CDC’s 2020 ADDM data:

• The prevalence gap between white children and children of other racial groups has narrowed significantly.
• In some surveillance sites, prevalence among Black, Hispanic, and Asian/Pacific Islander children now matches or exceeds rates among white children.
• Disparities in age of diagnosis persist, with children of color often being diagnosed later than white children.

Global Autism Prevalence

The World Health Organization estimates that approximately 1 in 100 children worldwide has autism. However, this figure likely underestimates true prevalence, as many countries lack the diagnostic infrastructure to identify all cases.

Countries with more developed healthcare systems and autism awareness campaigns tend to report higher rates, while countries with limited access to developmental specialists report lower rates. This difference reflects diagnostic capacity rather than actual differences in occurrence. Learn more about autism rates by country.

Why Are Autism Rates Increasing?

The increase in autism prevalence over the past two decades is primarily attributed to:

• Broader diagnostic criteria. The DSM-5 (2013) consolidated previously separate diagnoses (autistic disorder, Asperger’s syndrome, PDD-NOS) under one umbrella, identifying more people who would not have been diagnosed under older criteria.
• Better screening and awareness. Pediatricians, parents, and teachers are more aware of autism signs, leading to earlier and more frequent referrals for evaluation.
• Improved access to diagnosis. More communities now have access to developmental specialists, and telehealth options have expanded screening availability.
• Reduced stigma. As understanding of autism has grown, more families pursue diagnosis rather than avoiding the label.

Researchers continue to study whether any portion of the increase reflects a true rise in autism occurrence versus improved detection of existing cases.

Early Diagnosis and Intervention

The American Academy of Pediatrics recommends autism screening tool at 18 and 24 months. While autism can be reliably diagnosed as early as age 2, the average age of diagnosis in the U.S. remains around 4 years old.

Earlier diagnosis allows children to access evidence-based interventions like ABA therapy during critical developmental windows. Research consistently shows that children who begin intervention early have better long-term outcomes in communication, social skills, and adaptive behavior.

At Treetop ABA Therapy, we focus on getting families started quickly. We accept most insurance plans including Medicaid coverage in all states where we operate, and we serve families across multiple locations.

Frequently Asked Questions

How many people in the world have autism?

Based on the WHO’s estimate of 1 in 100 children and global population data, tens of millions of people worldwide are on the autism spectrum. The exact number is difficult to determine because many countries do not have comprehensive screening programs.

Is autism becoming more common?

Reported autism rates have increased significantly over the past two decades. Most experts attribute this primarily to improved awareness, broader diagnostic criteria, and better access to screening rather than a dramatic increase in the actual occurrence of autism.

What percentage of the population has autism?

In the United States, approximately 2.78% of 8-year-old children have been identified with autism, according to the CDC’s most recent data. Among adults, prevalence estimates are less precise but suggest roughly 2% of the adult population may be on the spectrum.

Why are boys diagnosed with autism more often than girls?

Boys are diagnosed with autism nearly four times more often than girls. This may partly reflect genuine differences in prevalence, but research increasingly suggests that autism in girls is underdiagnosed because girls tend to develop stronger social masking behaviors and may present with different symptoms than the traditional diagnostic criteria were designed to detect.

What should I do if I think my child might have autism?

Talk to your pediatrician about your concerns and request a developmental screening. If autism is identified, early intervention is key. Contact Treetop ABA Therapy to learn about our services and get started with ABA therapy with evidence-based support.