As a son of Iowa, Im no stranger to bragging about my home states ranking on various standardized test. Like Wisconsin we Iowans usually rank near the top of the heap on average ACT/SAT scores. We are usually joined there by Minnesota, Nebraska, and the various Dakotas; Vermont, Maine, New Hampshire
beginning to see a pattern? Perhaps because a states average ACT/SAT is, for all intents and purposes, a proxy for the percent of white people who live there. In fact, the lions share of state-to-state variance in test scores is accounted for by differences in ethnic composition. Minority students regardless of state residence tend to score lower than white students on standardized test, and the higher the proportion of minority students in a state the lower its overall test scores tend to be.
Please note: this has nothing to do with innate ability or aptitude. Quite to the contrary, I believe the test gap between minority students and white students can be attributed to differences in socioeconomic status. And poverty. And yes, racism. And yes, family structure. Whatever combination of reasons, the gap exists, and its mathematical sophistry to compare the combined average test scores in a state like Wisconsin (4% black, 4% Hispanic) with a state like Texas (12% black, 30% Hispanic).