what difference will the ’08 youth turnout make?

All the leading indicators suggest that youth turnout will reach about 50%–or maybe a little higher–which will come close to the record set in 1972. From a nonpartisan point of view, that’s a good thing because it means that more young people are interested and involved, which benefits them and society. Voting is a form of expression and it correlates with other forms of engagement, such as volunteering and following the news.

Of course, 50% is the proverbial glass that’s half-full and half-empty. We will still have a long way to go to match the youth turnout rates that are standard in other democracies. There will probably be 20-point voting gap between young people who have college experience and those who don’t–a clear equity problem.

From a partisan perspective, the higher the youth turnout, the better for Barack Obama. But Obama is currently far enough ahead that he wins under any plausible youth turnout scenario from most pessimistic to the most optimistic. This chart, from Gallup, shows the proportion of all voters who would be young, given various turnout scenarios, and what that would mean for the results of the election:

Obama wins under all these scenarios. But if the national race tightens by about 4 points, then the difference between Gallup’s lowest and highest youth turnout estimate will be the difference between President Obama and President McCain. (Or more precisely, it will determine who wins the popular vote.)