Phil asks where the turnout surge is. The answer is that it’s hanging out at Michael McDonald’s website:
My preliminary national turnout rate for those eligible to vote is 62.6% or 133.3 million ballots cast. This number may yet rise further as absentee ballots arrive and provisional ballots are processed, particularly in some western states. Until these outstanding ballots are counted, I would like to provide a conservative estimate. This turnout rate would be the largest since the 62.8% of 1964. If we top that number, which we might, the next highest turnout rate would be 63.8% in 1960.
For historic context, see McDonald and Popkin’s 2001 APSR piece on voter turnout. As an illustration, I have taken McDonald’s provisional estimate for 2008 turnout, and combined it with his (non-provisional) data on national turnout for Presidential elections in previous election years to make the graph below, which shows turnout trends since 1980.