Five points are made in this study. First, using a well‐recommended measure,interstateincome inequality is reported for each year from 1950 through 1989, and its very small magnitude is pointed out along with the U‐shaped profile. Second, it is shown that a simple quadratic‐form model fits the data extremely well. Third, inequality indices for 1977 and 1988 are recomputed after adjusting for interstate price‐level variations, and large reductions in the indices, and a virtual disappearance of the increase in inequality after 1978, are noted. Fourth, a simple decomposition shows that income changes account for most of the inequality change in each decade. Last, states that have contributed most to inequality are ide