Here we see the same story. The party whose primary turnout improved the most won the national popular vote in the general election two of five times and won the Electoral College three of five times. In 2000, Democrats saw a large decrease in primary turnout, while Republicans saw a large increase. That fall, we had one of the closest elections ever.
You might have noticed in the tables above that the Democrats in 2008 had the largest turnout and the largest increase in turnout. I suspect that many of the commentators who think the Republican candidate in the fall will benefit from higher turnout in the Republican primaries are remembering how Barack Obama easily won the general election in 2008. It turns out, however, that this pattern doesn’t hold when we look back in time.
Still, the 2008 campaign is instructive in another way. Democratic primary turnout was high because it was a very competitive contest. People turn out to vote when they think their vote may make a difference. Let’s re-examine the raw turnout for each party and the popular vote margin by which the nominee beat the runner-up in the primary.