“We must conclude with a troubling caveat, however. The norms sustaining our political system rested, to a considerable degree, on racial exclusion. The stability of the period between the end of Reconstruction and the 1980s was rooted in an original sin: the Compromise of 1877 and its aftermath, which permitted the de-democratization of the South and the consolidation of Jim Crow. Racial exclusion contributed directly to the partisan civility and cooperation that came to characterize twentieth-century American politics. The “solid South” emerged as a powerful conservative force within the Democratic Party, simultaneously vetoing civil rights and serving as a bridge to Republicans. Southern Democrats’ ideological proximity to conservative Republicans reduced polarization and facilitated bipartisanship. But it did so at the great cost of keeping civil rights—and America’s full democratization—off the political agenda.”