Generational Polarization

Were poor youth turnout and high elderly turnout responsible for the Democratic slaughter on Tuesday?  William Galston is skeptical:

The conventional wisdom before November 2 was that seniors enraged or terrified by changes in Medicare would turn out in droves to punish those who voted for health reform while young people disillusioned by Obama’s failure to create the New Jerusalem would abstain. That did happen, but only to a modest degree. Voters of ages 18-29 constituted 12 percent of the electorate in 2006; 11 percent in 2010. Voters over 65 were 19 percent of the total in 2006; 23 percent in 2010—noticeable but hardly decisive.

Okay, but Galston ignores an important trend: the electorate has polarized by age group considerably since 2006.  In 2006, 60% of 18-29 year olds voted Democratic, compared to 49% of 65+ voters.  That's an 11-point difference.  In 2010, 57% of 18-29 year olds voted Democratic, compared to 38% of 65+ voters.  That's a 19-point difference.  The increasing Democratic tendency of young voters relative to older voters made their failure to vote much costlier for Democrats than it would have been a few years ago.