— US state cognitive research
Average IQ in California
Published state-level cognitive ability research places California at an estimated average IQ of around 99. These estimates carry wide confidence intervals and should be interpreted as rough population averages, not precise measurements.
California's state-wide average is close to the national mean, though Silicon Valley and Bay Area populations perform well above average. The large immigrant population and high income inequality affect the overall figure.
Why state IQ averages differ
State-level IQ differences in the US are largely explained by:
- Educational spending per pupil — states that invest more in K-12 education see higher average cognitive test performance
- Income inequality — childhood poverty correlates strongly with cognitive test performance due to nutrition, stress, and access to stimulating environments
- Migration patterns — states with large educated immigrant inflows (California, New York, Virginia) score differently than net-outflow states
- Industry mix — tech-heavy states attract highly educated workers, raising the state average
- Urban concentration — virtually all states show urban areas outperforming rural areas by 8-12 IQ points
States with similar average IQ
- Average IQ in Iowa — estimated 101
- Average IQ in Montana — estimated 101
- Average IQ in Washington — estimated 101
- Average IQ in Kansas — estimated 101
- Average IQ in Oregon — estimated 100
IQ vs educational outcomes
State IQ estimates correlate strongly (r ≈ 0.7) with NAEP (National Assessment of Educational Progress) scores, which are independently measured. This gives the estimates some external validity. The correlation also illustrates that IQ is bidirectional with education — better schools produce higher test scores and better test preparation environments.