@timeoflifehaver: Yes, though the correlation doesn't rule out alternative explanations to vote suppression. The pattern is also consistent with a population divided into motivated and apathetic toward voting. Motivated people both register and vote, apathetic people do neither, even if there is no suppression of registration or voting. One way to figure out which of these two explanations is operating would be to assess motivation to vote and compare it with registration and voting. If some highly-motivated folks do not register or vote, that would be more evidence for suppression--or at least barriers to voting if not outright suppression--than it would be evidence for a divided on motivation.
Also possible that suppression in some way causes the motivation-apathy divide, with people who have been historically suppressed becoming apathetic as a means of psychologically dealing with suppression, and people who have been historically privileged by voting and the political system becoming motivated about democracy as a means of psychologically dealing with participating in and benefiting from a government based on suppression that benefits them.
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