On August 6, Johnson signed the Voting Rights Act of 1965, which suspended literacy tests and other subjective voter registration tests. It authorized Federal supervision of voter registration in states and individual voting districts where such tests were being used and where African Americans were historically under-represented in voting rolls compared to the eligible population. African Americans who had been barred from registering to vote finally had an alternative to taking suits to local or state courts, which had seldom prosecuted their cases to success. If discrimination in voter registration occurred, the 1965 act authorized the Attorney General of the United States to send Federal examiners to replace local registrars.

Within months of the bill's passage, 250,000 new black voters had been registered, one-third of them by federal examiners. Within four years, voter registration in the South had more than doubled. In 1965, Mississippi had the highest black voter turnout at 74% and led the nation in the number of black public officials elected. In 1969, Tennessee had a 92.1% turnout among black voters; Arkansas, 77.9%; and Texas, 73.1%.