http://www.salon.com/2015/03/01/our...i_minority_bias_is_even_worse_than_you_think/ Much of the extant literature has mainly been focused on voter ID laws; but Vandewalker and Bentele find that the strategy is actually more expansive than that. They have created an extensive metric that includes nine different measures of accessibility, including voter ID, absentee voting and same-day registration. They find that the accessibility of voting systems is negatively correlated with the share of the state’s population that is black (see chart). As the black population increases, voting systems become more inaccessible. The chart below includes all changes that were passed in the legislature; as of writing some of the changes were stalled in court. The study finds that between 2006 and 2012, the most influential factor in determining whether a law would be passed was Republican control of government. It also finds that the level of anti-black stereotyping in a state (a measure based on survey respondents’ beliefs about work ethic and intelligence) strongly correlates with the proposal (though not the passage) of voting restrictions.