Photo of an ethnically diverse group of 4-year-old girls and boys holding hands and smiling.

Findings from 2020 data

How many 4-year-old children were identified with ASD in Minnesota?

1.9% or 1 in 53 children were identified with ASD in Minnesota.

Using data from 2020, MN-ADDM researchers found 1 in 53 (1.9%) 4-year-old children were identified with ASD. This is lower than the overall ADDM Network prevalence of 4-year-old children identified with ASD (1 in 46 or 2.2%) in the United States where the CDC tracked ASD in 2020.

When were 4-year-old children first diagnosed with ASD in Minnesota?

Cumulative incidence refers to the rate of identification over time. Compared with children aged 8 years, Minnesota 4-year-olds had a higher cumulative incidence than 8-year-olds, meaning ASD identification is happening at a faster pace in the younger age group than the older age group. Minnesota 4-year-olds were identified at 1.5 times the rate of 8-year-olds.

ASD identification of Minnesota 4-year-olds had an incidence of 1.5 times the rate of 8-year-olds, which is higher than the incidence rate of 1.6 times the rate of 8-year-olds of all ADDM sites.

What was the percentage of 4-year-old children with ID in Minnesota?

Minnesota had intelligence quotient (IQ) data available for 75% of 4-year-old children identified with ASD. 62% had IQ less than or equal to 70. 38% had IQ greater than or equal to 70.

This information is based on the analysis of data collected from the health and educational records of children who were 4 years old in 2020. In addition to the race/ethnicity categories routinely studied by CDC, in MN we are interested in understanding prevalence for children in our Hmong and Somali communities. Please check back for updated analyses including Hmong and Somali children.

Which children were more likely to be identified with ASD in Minnesota?

Among 4-year-olds, boys were 3.3 times more likely to be identified with ASD than girls.

Prevalence of ASD in 4-year-old children in Minnesota by sex/gender, race and ethnicity

Prevalence estimate

Prevalence per 1,000 children

95% confidence interval per 1,000


1 in 53





1 in 34





1 in 37




Asian or Pacific Islander

1 in 53




Black, Non-Hispanic

1 in 43





1 in 41




White, Non-Hispanic

1 in 76




Two or more races

1 in 53




American Indian or Alaska Native children were included in the denominator but were not included in prevalence estimations due to low numbers of children with ASD

*Wilson score 95% CIs exclude 1.0, indicating significantly higher prevalence.

Males had a higher ASD prevalence than females.

Asian/Pacific Islander children had higher ASD prevalence than White children.

Black children had higher ASD prevalence than White children.

Hispanic children had higher ASD prevalence than White children.

What do the sex and race/ethnicity differences in prevalence rates tell us?

Males aged 4 years had a higher ASD prevalence 4.1 times higher than females aged 4 years.

Asian/Pacific Islander, Black, and Hispanic 4-year-old children had a higher ASD prevalence than White 4-year-old children. Prevalence for Asian/Pacific Islander children was 1.4 times that of White children, prevalence for Black children was 1.8 times that of White children, and prevalence for Hispanic children was 1.8 times that of White children. A prevalence ratio of 1.0 indicates equal prevalence rates. The confidence intervals for prevalence ratios for these groups were all greater than 1.0, meaning these findings were very likely not due to chance.

Tracking Area

The tracking area included parts of three counties (Anoka, Hennepin, Ramsey) including the large metropolitan cities of Minneapolis and Saint Paul.

4-year-old children in the tracking area included 16,326 children of the following race and ethnicity

  • American Indian or Alaska Native - 1%
  • Asian or Pacific Islander – 16%
  • Black, non-Hispanic – 23%
  • Hispanic –11%
  • White, non-Hispanic – 43%
  • Two or more races – 7%


This is the fourth time Minnesota data has been included in findings from the ADDM Network and the second time we have included 4-year-old prevalence. Overall prevalence of ASD among 4-year-olds in 2020 (1 in 53) was 18% lower than prevalence among 4-year-olds in 2018 (1 in 44). The portions of Ramsey and Hennepin counties included in prevalence estimates differed in 2018 and 2020, which may have impacted prevalence estimates. Prevalence rates for Black and Hispanic children were similar from 2018 to 2020, while rates for White and Asian/Pacific Islander children were lower in 2020.

In Minnesota, there are differences between the proportions of 4-year-old males and females identified with ASD, with more males than females. This is consistent with previous estimates and with estimates across the ADDM network. (Note: the ADDM project only collects data on male and female sex as indicated in records and does not include gender identification information.)

In Minnesota, we identify ASD much later than when first concerns are reported. The median age of the first ASD diagnosis for 8-year-olds was 4 years and 11 months, which was the latest age across the ADDM Network. We found that 4-year-old children are being identified with ASD at 1.5 times the rate of 8-year-olds, which indicates that identification is happening more frequently at earlier ages, but the late age of identification remains concerning due to the critical importance of early identification and intervention. Many states, including MN, have invested in early intervention to help children and families gain access to early intervention services. For example, Minnesota’s Early Intensive Developmental and Behavioral Intervention (EIDBI) Benefit provides early intensive intervention for people with ASD and related conditions. To learn more about the EIDBI benefit follow this link:

We found varying prevalence rates across racial and ethnic groups in Minnesota. The small number of children in some of these groups makes it difficult to determine whether the rates of children with ASD truly are different across groups. When differences are found, it is important to focus on general health disparities that may influence these differences.

We found that among 4-year-old children with IQ information, 62% had an intellectual disability, compared to 32% for 8-year-olds. The higher rate of intellectual disability in the younger group is not unexpected, as children with ASD with developmental delays are often identified earlier than children with ASD without developmental delays.

Minnesota experienced marked reductions in ASD evaluations and identifications with the onset of the COVID-19 pandemic in March 2020. These reductions persisted through the end of 2020 in Minnesota and two other states, while 8 ADDM sites showed a recovery of evaluations and identifications to close to pre-pandemic levels.


The findings in this report reflect a small number of children concentrated in a large metropolitan area and may not reflect prevalence across the entire state.

The numbers of 4-year-old children with ASD from some racial/ethnic groups are small, and their prevalence estimates will be less precise than estimates for larger-sized populations. Confidence intervals show the range in which we are 95% confident that true prevalence lies, and a larger confidence interval means less precision (e.g., 14.4–25.0 for Asian/Pacific Islander children). This tells us we should use caution before drawing conclusions about differences between some groups.

MN-ADDM reviewed records from participating public school special education programs but did not review private school education records or all charter school education records in our geographic area. Similarly, if a child was identified with ASD in a clinic outside of those included in MN-ADDM’s geographic area, their health records may not have been captured. Incomplete information could lead to misclassifying children’s cognitive ability, overestimating the age when they were first evaluated or when ASD was identified, or failing to capture that the children were identified as having ASD.