Has the 2008 election ushered in a new era of Democratic hegemony, akin to those enjoyed by the Democrats beginning in 1932 and the Republicans beginning in 1980? Two considerations suggest yes.
First, a Republican president is presiding over a deep economic crisis. The early-1930s and late-1970s crises scarred the party in power for a generation, and this one has the potential to do the same (John Judis makes a similar point).
Second, Barack Obama won big among young voters; according to exit polls, he got 66% of the votes of those age 18 to 29. This is important because while our party preference can in principle change at any time, we tend to stick with the party we identified with when we first became politically aware.
The following two charts show the role this played in the partisan shift that occurred around 1980. Both use data on party identification from the National Election Study (NES) and the General Social Survey (GSS). In the first chart, we see that among all American adults Democrats held a large advantage until the late 1970s, after which their edge diminished sharply. The second chart shows the trend for people who turned age 20 between 1978 and 1990. The formative political years for this cohort were ones of economic crisis under Democrats in the late 1970s followed by improvement (after 1982) under a Republican president and Senate in the 1980s. Among this group the party identification gap started small and had virtually disappeared by the mid-1980s. Through the 1980s, 1990s, and 2000s this cohort has slowly replaced an older generation of Americans who continued to identify with the Democrats. This process of cohort replacement is a key driver of the shrinking partisan gap among all adults that we see in the first chart.
Are we in the midst of an enduring shift in favor of the Democrats? We’ll only be able to tell in retrospect, of course, and I suspect much hinges on what the Obama administration can accomplish. But the groundwork appears to have been laid.