The new century saw a hardening of institutionalized racism and legal discrimination against citizens of African descent in the United States. Throughout this post Civil War period, racial stratification was informally and systemically enforced, in order to solidify the pre-existing social order. Although technically able to vote, poll taxes , pervasive acts of terror such as lynching in the United States (often perpetrated by groups such as the reborn Ku Klux Klan , founded in the Reconstruction South), and discriminatory laws such as grandfather clauses kept black Americans (and many poor whites ) disenfranchised particularly in the South. Furthermore, discrimination extended to state legislation that "allocated vastly unequal financial support" for black and white schools. In addition to this, county officials sometimes redistributed resources earmarked for blacks to white schools, further undermining educational opportunities.  In response to de jure racism, protest and lobbyist groups emerged, most notably, the NAACP (National Association for the Advancement of Colored People) in 1909. 
In sum, Katrina provides an unprecedented opportunity to communicate that “racism” is not just a matter of the psychology of hatred but is instead also a matter of the racial structure of political and economic inclusion and exclusion. This is one lesson from Katrina that social science should help communicate. Moreover, we should not blinker ourselves: this message is one that is deeply opposed by powerful political forces in the United States today. Those who deny the social nature of racism (whether substantively or methodologically) may not be bigots, but they are undoubtedly abettors of racism in the social sense of the word.