A new Century Foundation report shows that African-Americans are silently disenfranchised by
outdated voting machines.
African-American votes disproportionately go uncounted when punch-card and, to some extent, "central count" optical-scan machines (where ballots are scanned and counted in a central location) are used. In contrast, the racial disparity nearly disappears when electronic voting machines and "precinct count" optical scan machines are used (Scan equipment based in precincts can be programmed to detect and reject mistakes and allows voters to fix them before leaving the polling place). This is true even when controlling for other factors such as income and education.
Of course, more than 90% of African-Americans vote Democratic, so these outdated machines may prove just as effective as Katherine Harris' voter scrub list.