Republicans follow a v-shaped pattern: They became significantly younger under Reagan and George H.W. Bush as compared to under Richard Nixon and Gerald Ford. But they have grown older again since. The average “strong Republican” was 52.3 years old in the 2010 and 2012 versions of the survey.
The age of “strong Democrats” has been steadier, ranging between 48.6 and 49.9 years under each president from Nixon to George W. Bush. However, their average age has actually increased, to 50.7 years, under Obama.
The Americans who identify as strong partisans and who take the most active interest in politics are older still. In 2012, the General Social Survey asked Americans how informed they were about politics. Those who described themselves as strong Democrats and said they knew “quite a bit” or a “great deal” about politics were 52.7 years old, on average. The strong Republicans who said the same were 53.6 years old.
It’s very important to emphasize that these results do not imply that young people are uninterested in political affairs. Political movements ranging from Ron Paul’s campaigns in 2008 and 2012 to Occupy Wall Street to the push for gay marriage have been full of young people.