2008 set the record for first-time voters
CIRCLE was recently asked whether more first-time voters participated in 2008 than ever before. The answer seems to be yes:
We are not able to calculate these figures for years before 1984, but the growth in the adult population has been sufficient that it is extremely unlikely that more than 14.6 million first-time voters ever participated in an election. That makes 2008 the record year. On the other hand, the proportion of voters who were first-timers could have been higher in previous years. In proportional terms, 2004 and 2008 were similar and higher than other recent years.
Sources: Exit poll data archived by The New York Times; turnout data compiled by the American Presidency Project from the Federal Election Commission and other sources.