Turnout rates are easy to define: You divide the number of people who voted into the number of people who could have voted. But they're hard to calculate in the U.S. The 50 states and the District of Columbia run the show, and they generally don't keep an accurate count of eligible voters. "The quality of electoral reporting past and present, like the underlying quality of the effort to organize coherent elections, has varied extremely widely across the fifty states," Walter Dean Burnham, professor emeritus at the University of Texas and longtime turnout researcher, wrote in a paper in December.
The Wall Street Journal
Voters Flock to Polls, But Are They Really Reversing a Trend?