© 2018 Hogrefe Publishing. Economic development and national intelligence decline with proximity to the equator. Absolute latitude associates with both, income and IQ, but the nature of their relationship is ambiguous. This study applied structural equation modeling using secondary data pertaining to the 48 contiguous states of the United States of America to test the hypothesis that UV (ultraviolet) radiation associates with income through complex cognitive ability vis-a-vis the hypothesis that UV radiation associates with complex cognitive ability through income. The resulting evidence was consistent with the ability ? income pathway and unsupportive of the income ? ability model. The findings uphold the cognitive capitalism perspective and may throw light on the evolvement of regional differences in the USA.