Do the leading predictors of economic growth found in the cross-national research have a capacity to predict economic growth at the state level in the United States (US)? Are the effects of education spending on economic growth underestimated because research fails to examine the indirect effects of spending on economic growth? This article presents the findings from a study investigating the relationship between education and economic growth in US states while controlling for the effects of the leading predictors of economic growth from the cross-national research. It also utilizes a path model to examine direct and indirect relationships between education spending and economic growth measured as per capita income growth. The results indicate that spending on higher education and highway expenditures demonstrate a positive association with growth in per capita income, while K12 (kindergarten through 12th grade) spending and K12 pupil–teacher ratios demonstrate a negative association with income growth from 1988 to 2005. Moreover, K12 spending and population growth indirectly affect income growth through their relationship with K12 pupil–teacher ratios, and spending on higher education indirectly affects income growth through college attainment rates. Overall, all but one variable from the cross-national research demonstrates a significant direct or indirect relationship with income growth during at least one time-period investigated. Treating K12 pupil–teacher ratios and college attainment as mediating variables also enhances our understanding of the dynamics that explain growth in per capita income at the sub-national level in the US. However, some unexpected findings emerge when the data are analyzed on the basis of two eight-year sub-periods.