Link to spreadsheet.
The preferred turnout rates are those calculated with the voting-eligible population as the denominator. The voting-eligible population (VEP) represents an estimate of persons eligible to vote regardless of voter registration status in an election and is constructed by modifying the voting-age population (VAP), by components reported in the right-most columns (scroll right in the spreadsheet).
Questions? Please see the FAQ.
The demoninator data reflect the July 1, 2008 and July 1, 2009 voting-age population estimates (2010 intercensial adjustment) interpolated to Nov. 2008, non-citizen estimates from the 2008 and 2009 American Community Surveys interpolated to Nov. 2008, the year end-year 2008 DOJ prison report and the end-year 2008 DOJ probation and parole report. The overseas eligible estimate is recently updated with data provided by the Federal Voting Assistance Program.
Special Note on Overseas Citizen Population: This is the first (and only) election where I have apportioned overseas voters to the states from information reported by the Federal Voting Assistance Program. In the other elections I only estimate a national overseas citizen population. For consistency with previous elections, in the turnout rates reported here the national VEP adjusts for overseas citizens, but the state VEPs do not. State level overseas citizens estimates are provided for those who wish to further adjust state level turnout rates for overseas citizens.