The author says about turnout: "One clarification: The turnout number at the bottom is slightly wrong: You’d think that you can easily get these statistics for past elections, but I can’t find the turnout number anywhere. Instead I was able to get the population of the counties, so this is the number of votes divided by the population." Isn't this quite inaccurate? I think counties release registered voter numbers, s…
Numbers for each state since 2000, every 2 years, available here: http://www.electproject.org/home/voter-turnout/voter-turnout...
What you want is probably the VEP number ("voting-eligible population", people who are of age and not disqualified for some reason, such as having committed a felony).