Updated IQ and Well-Being Scores for the 50 U.S. States
ncbi.nlm.nih.gov
ncbi.nlm.nih.gov
The whole thing is kind of misleading because the correlation exists but isn't through the roof.
In general, I think the relationship between all of these measures could make a good example of Simpson’s paradox. It’s likely completely different correlations could be supported if the data were analyzed at the county level or if it were possible to completely disaggregate down to individuals.