18-29 year olds are left leaning. Kerry won them by about 10 points, even though he lost to Bush by 3 points overall.
And remember, young voters tend to get more conservative with age. Barack Obama had a very special appeal among these voters, which is why he won 66% of them nationally. If it was a generic Dem who won the popular vote by 7%, I'd expect the 18-29 year olds to give the Dem about 60%.
One thing about young voters is that are quite liberal on social issues, like gay marriage. If the majority of the GOP doesn't support gay marriage, or at least civil unions, it will hurt them in the long run.
Young voters have typically been more liberal -- or at least libertarian -- than older voters on sexuality. On other issues? It varies greatly.
As people get older they tend to have more of a stake in the
status quo; their incomes increase and so do the economic demands upon them (children). Advancement in corporate bureaucracies -- a norm for adults now 55+, but not so obvious for those under 55 -- depends in part on having the same values as management. Of course, with blue-collar workers one might trust one's union more than the corporate executives, in which one tends to become more liberal-leaning as time passes, and if one works for a government agency, one has an entrenched interest in the expansion of one's bureaucracy. One tends to become more conservative -- or more liberal, depending on one's environment.
What Howe and Strauss call the Millennial Generation (born 1982 until at least 2000) may have seen contemporary politics and economics at their worst. The older generation, Generation X (born 1961-1981) typically remembers the Fall of Communism, the successful overthrow of Manuel Noriega and the liberation of Kuwait. Generation X recognized some certainty in low-paying jobs in malls and restaurants -- jobs that at the least offered the chance to buy up chic clothing and improving electronic goodies at falling prices. Only after they started getting into their 20s did Generation X realize that they were being $crewed -- and they complained about what Big Business was doing to them in the presence of younger people (the Millennial Generation) as mass layoffs solely to cut wage costs (often by shipping manufacturing overseas) put an end to industrial jobs. The Millennial Generation learned even before they entered the workforce that Corporate America was a place of glass ceilings for all but a few and piked pits for most.
Add to that, the Millennial Generation had knowledge of the sleazy era of Bush 43-era politics and economics from first-hand experience, but all else from second-hand knowledge, as from textbooks. So it was in November 2008. They were old enough to know of the glory-seeking of a President whose "Mission Accomplished" left far too much unsolved. They saw the bungled response to Hurricane Katrina. They saw the effects of the subprime lending/ real estate bubble going bust. They knew that inequality in America was intensifying while economic security vanished. They saw an unusual number of political scandals -- scandals more intense and pervasive than Watergate, thank you. The Civics and American history textbooks told them of Presidents far more coherent in their addresses to the American people and of more prosperous times -- times inconsistent with Dubya. They might have stayed up late on occasion and seen Leno or Letterman lampoon Dubya. Letterman had sketches in which he contrasted FDR's "We have nothing to fear but... Fear itself!" and JFK's "Ask not what your country can do for you" to the babbling of recent days from the current President.
So youth born after 1981 had little stake in the preservation of the political or economic
status quo while they America had a very conservative Administration and Congress and while Corporate America acted harshly toward anyone not an Insider. That's one way to become liberal. (Conservatives may count their blessings; if America had a latent Socialist movement, then it might have expanded rapidly in recent years!) If there was anything good in American history it was in something much unlike the Bush administration and in business executives being paid very well for treating people very badly.
Americans, but especially young Americans, wanted change -- and they got its prospect in the Presidential candidate most unlike Dubya.