Among the cohort of Americans caught by 9/11 in their formative years, the effects of the attacks on their civic consciousness were more enduring. The annual UCLA chart of interest in politics jumped upward in 2001 for the first time in decades and has kept rising every year since.

For most Americans the half-life of the civic boomlet after the attacks was barely six months. Within a year measures of civic engagement had returned to the previous levels, from which they have barely budged since. Except among young people.

Then came the attacks of Sept. 11, 2001, a national tragedy, but also a vivid reminder that we are all in this together. Civic seismometers across the land showed a sharp spike in virtually every measure of community-mindedness. It was, I wrote at the time, not only a tragedy, but also the sort of opportunity for civic revival that comes along once or twice a century. Just as Pearl Harbor had spawned the civic-minded "Greatest Generation," so too Sept. 11 might turn out to produce a more civically engaged generation of young people.

Thirty-four years later that figure had plummeted to 28 percent. In 1972, when the vote was first extended to 18-year-olds, turnout in the presidential election among 18- to 24-year-olds was a disappointing 52 percent. But even beginning at that modest level, rates of voting in presidential elections by young people steadily fell throughout the '70s, '80s, and '90s, reaching barely 36 percent in 2000. National commissions bemoaned the seemingly inexorable increase in youthful apathy and incivism. The National Commission on Civic Renewal said, "When we assess our country's civic and moral condition, we are deeply troubled. . . . We are in danger of becoming a nation of spectators."

Throughout the last four decades of the 20th century, young people's engagement in American civic life declined year after year with depressing regularity. In fall 1966, well before the full flowering of Vietnam War protests, a UCLA poll of college freshmen nationwide found that "keeping up with politics" was a "very important" goal in their lives for fully 60 percent.

IN THE mushrooming procedural debate about Democratic superdelegates and the uncontested Florida and Michigan primaries, more is at stake than the identity of the presidential nominee or even the Democrats' chances of victory in November. Primaries and caucuses coast to coast in the last two months have evinced the sharpest increase in civic engagement among American youth in at least a half-century, portending a remarkable revitalization of American democracy. But that rebirth of American civic life would be aborted if the decision rendered by millions of ordinary Americans could be overturned by a backroom deal among political insiders. The issue is not public jurisprudence or obscure party regulations or the alleged "wisdom" of party elders, but simple playground notions of fairness.

Last month the UCLA researchers reported that "For today's freshmen, discussing politics is more prevalent now than at any point in the past 41 years." This and other evidence led us and other observers to speak hopefully of a 9/11 generation, perhaps even a "new Greatest Generation." In the 2004 and 2006 elections, turnout among young people began at last to climb after decades of decline, reaching the highest point in 20 years in 2006. As we approached the presidential season of 2008, young Americans were, in effect, coiled for civic action, not because of their stage of life, but because of the lingering effects of the unifying national crisis they had experienced in their formative years.

The exceptionally lively presidential nominating contests of this year - and, it must be said, the extraordinary candidacy of Barack Obama - have sparked into white hot flame a pile of youthful kindling that had been stacked and ready to flare for more than six years. The 18-year-olds first eligible to vote in 2008 were in sixth grade when the twin towers fell, and their older sisters and brothers who were college seniors in September 2001 are now 28 or 29. It is precisely this group, above all others in America, that has pushed participation rates in this spring's caucuses and primaries to record levels. Turnout in this spring's electoral contests so far has generally been higher than in previous presidential nominating contests, but for twentysomethings the rise has been truly phenomenal - turnout often three or four times greater than ever before measured.

The 2008 elections are thus the coming-out party of this new Greatest Generation. Their grandparents of the original Greatest Generation were the civic pillars of American democracy for more than a half-century, and at long last, just as that generation is leaving the scene, reinforcements are arriving. Americans of every political persuasion should rejoice at this epochal swing of the generational pendulum, for it portends precisely the sort of civic renaissance for which Jeremiahs have been calling for many years.

This, then, is what is at stake in the otherwise inside-baseball controversies about superdelegates and pledged delegates and the uncontested Florida and Michigan primaries - controversies now roiling Democratic party leaders. If the results of the caucuses and primaries are, despite record-breaking rates of popular participation, overturned by unelected (though officially legitimate) superdelegates or by delegates from states that all candidates had previously agreed not to contest, the lesson for the young civic stalwarts would be unmistakable - democratic politics is a sham. Politics is actually controlled by party bosses behind the scenes. Civic engagement is for suckers.

From Little League to student council races, we all learn to accept defeats we have lost fair and square. But losing in a contest in which the rules can be rigged teaches that the game is not worth the candle. Who can honestly doubt that if the Democratic presidential candidate preferred by a majority of the delegates elected in this spring's competitive contests (and by the overwhelming majority of young voters) were to be rejected solely by the power of unelected delegates (or those "elected" without any serious competition), the unmistakable civics lesson would be catastrophic for this incipient cadre of super citizens?

So as the superdelegates, the two campaigns, and Democratic Party leaders contemplate how to resolve the procedural issues before them - what to do about Michigan and Florida, and how superdelegates should vote - let's hope that they weigh the consequences not merely for their own candidates this year, and not merely for the Democratic prospects in the fall, but for the future vitality of American democracy.

Robert D. Putnam, a professor of public policy at Harvard University's John F. Kennedy School of Government, is author of "Bowling Alone: The Collapse and Revival of American Community" and "Better Together: Restoring the American Community."

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