There is mounting evidence of substantial “teacher quality gaps” (TQGs) between advantaged and disadvantaged students, but practically no empirical evidence about their history. We use longitudinal data on public school students, teachers, and schools from two states—North Carolina and Washington—to provide a descriptive history of the evolution of TQGs in these states. We find that TQGs exist in every year in each state and for all measures we consider of student disadvantage and teacher quality. But there is variation in the magnitudes and sources of TQGs over time, between the two states, and depending on the measure of student disadvantage and teacher quality.