Quick Answer
The US national average IQ is approximately 98, slightly below the global mean of 100 due to how the tests are normalized. The US ranks around 25th globally. Massachusetts leads among states at an estimated 104.3.
Why the US average is 98, not 100
The global mean of 100 is set relative to the norming population of each test - not a single worldwide standard. The US national average came out at 98 in Richard Lynn and Tatu Vanhanen's data (IQ and the Wealth of Nations, 2002) because the US sample was compared against the international benchmark used for that study.
State-level IQ data is even more uncertain. Most estimates come from SAT/ACT score conversions, NAEP (National Assessment of Educational Progress) scores, and military AFQT data - not direct IQ testing. The figures below should be treated as rough proxies, not precise measurements.
Top 10 US states by estimated IQ
| State | Estimated Average IQ |
|---|---|
| Massachusetts | 104.3 |
| New Hampshire | 104.2 |
| North Dakota | 103.8 |
| Vermont | 103.8 |
| Minnesota | 103.7 |
| Connecticut | 103.1 |
| Wisconsin | 102.9 |
| Kansas | 102.8 |
| Iowa | 102.5 |
| Nebraska | 102.5 |
The Northeast and upper Midwest cluster at the top. This pattern likely reflects educational investment, demographics, and economic factors rather than innate regional differences. States with more research universities and higher median incomes tend to score higher on any cognitive proxy measure.
How US IQ compares globally
| Country | Estimated Average IQ | Global Rank |
|---|---|---|
| Singapore | 108 | 1 |
| Hong Kong | 108 | 1 |
| South Korea | 106 | 3 |
| Japan | 105 | 4 |
| China | 105 | 4 |
| United States | 98 | ~25 |
| United Kingdom | 100 | ~15 |
| France | 98 | ~25 |
East Asian countries consistently top the international rankings. Researchers point to cultural emphasis on education, high-quality school systems, and dietary factors including omega-3-rich diets. The US ranking reflects its status as a large, diverse nation with significant educational inequality across regions.
IQ by age in the US
IQ scores are age-normed, so the average is always 100 within each age group by definition. What changes with age is the composition of that average: fluid intelligence peaks in the mid-20s, while crystallized intelligence grows through the 60s. Adults aged 35-55 typically show the most balanced cognitive profile.
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