"In Presidential election years between 1972 and 2000, the national youth voter turnout rate declined by 13 percentage points (among 18-24 year old voters)."
"In 2000, 42% of 18-24 year old citizens voted; 70% of citizens 25 and older voted." (SOURCE)
The archetypal voter is old, rich, white, has kids (maybe adult kids, but has kids), has lived in the same city, and possibly same house (which they own, or have a mortgage on), for five years, and is well-educated.
Young people move around a lot, whether going to college or just looking for jobs. So, they tend to put off registration, particularly in states without "Motor Voter" registration. But even if they register, they are less likely to vote. Some of this can be explained by the fact that they make lower incomes, and are more likely to rent. So it is easy to confuse "young" with "moves a lot, has low income, and rents".
Controlling for those things, young people STILL vote less. (Can the kids be charted?)
The young are more likely to want to make their own choices, and reject the alternatives that the established parties offer ("I don't drive my father's Buick, and I don't vote for my father's party"). But this changes fairly quickly. Most voters end up pretty close to their parents, in terms of partisan affiliation.
So, does any of this matter, in this election?
Two schools of thought: (a) war and appearance of corruption of political system (the Michael Moore conspiracy theory of government) will turn young citizens off, or (b) war, possible draft, and experience of young people directly with government functioning badly will make them take an interest.
Predictions are tough, but I lean toward (b): I think turnout among the young will go up this election. But that would require that registration starts taking place NOW. Democrats don't seem to be working on this much, and since new youth voters are likely to vote Dem the Repubs have little reason to pursue youth turnout drives. (But see this chat with the Repub Youth Director).
And, there's always this. Oh, sweet mercy. It's a thing o'beauty: Huge men in tights, telling me to vote or they will sweat on me. I think K. Grease will need to be alone for a few minutes now.