Before 1965, you had to pass a literacy test to vote in Alabama. (The primary purpose was to keep minorities from voting.) There seem to be multiple variations of the test here, here and here. Supposedly you had 8 minutes and were allowed only 2 wrong answers. Frank and I took the 30 question version in Uncle John's Triumphant 20th Anniversary Bathroom Reader and we only got half of them! Guess we wouldn't have been voting.
It wasn't a literacy test – it was a "do you know the constitution and US government" test.