How much does spending vary across US public schools? And how much do the schools that low-income students attend spend compared to schools attended by their more advantaged peers? Students are educated in schools, which are frequently segregated by race and socioeconomic status, and spending can vary across schools within the same district. But this variation is invisible in revenue and expenditure data reported and analyzed at the district level, rather than school level, as has typically been done in the school finance literature to date (because of data limitations). Because the scope for within-district spending inequality is greater in larger districts that have many schools, differences in the number of schools per district may distort comparisons across states. To illustrate this phenomenon we analyze two states: Florida, which has 67 regular school districts, and Illinois, which enrolls fewer students in total, but has nearly 900 regular school districts. We construct measures of inequality and progressivity using school-level and district-level data. We show that across-school, within-district inequality is indeed higher in Florida than in Illinois. As expected, comparisons of inequality and progressivity based on district-level averages exaggerate the differences between the two states.