Heather Smith, executive director of Rock the Vote, wrote this week, “At the risk of sounding self-absorbed, it’s not just about Barack Obama, it’s about us.” Smith seeks to rebut the sense that the youth-vote craze is Obama-driven.

She’s right. Youth vote hype has been around. In 2004, when “meetups” were the rage, Rock the Vote preened and registered more than a million voters. In 2006, they pounced on Facebook’s social networking and Heather gushed,

“Once young people are registered to vote, it is easy for campaigns and candidates to target and turn them out to the polls.” Oh, the idealism of youth! But does reality support Heather’s enthusiasm?

Campaigners must set aside normative wishes about kids voting and be realistic about the likelihood of that happening. Regrettably, youth vote boosters like Heather induce too many candidates and campaigns to place too much emphasis and hope on that unreliable slice of the electorate. If Barack Obama wants to build his entire campaign on exciting the youth vote, then as a Republican I hope he does exactly that, because it will lead to his defeat. The hard numbers don’t lie.

The Census Bureau biennially undertakes studies known as “Voting and Registration in the Election of [Year].” These surveys are invaluable in separating claims from reality regarding the youth vote. Consider these results from the 2004 survey: 14.3 million Americans ages 18 to 24 were registered to vote, 51.5 percent of that age cohort. An impressive 11.6 million, or 81 percent, of these young registered voters said they cast a ballot. Sounds pretty good, and may validate some of Heather’s optimism about young registered voters, but the more compelling number may be that 58.1 percent of the entire 18- to 24-year-old cohort didn’t vote. That doubles non-voting among 65- to 74-year-olds, only 29.2 percent of whom didn’t vote.

Senior turnout is particularly impressive when you consider that many elderly citizens must overcome some infirmity to vote. The 2004 census study suggests this in its analysis of why voters didn’t go to the polls. Among voters 65-plus who didn’t vote, 46 percent blamed illness or disability. By comparison, just 3 percent of 18- to 24-year-olds could use this excuse. The most common justification by youth was simply being “too busy” or having a “schedule conflict,” categories mentioned by 23.3 percent of them. More troubling is that 15.2 percent of young voters could articulate absolutely no rationalization for their failure to vote, twice the shiftlessness of any other age category.

Looking deeper into the patterns of voting by youth ages 18 to 24, it’s evident that lifestyle and life circumstances make a difference. For example, while young Americans with incomes of $100,000 or more vote at a clip of 63 percent, those with incomes of less than $30,000 vote at a rate of 30 percent or less. Married young couples go to the polls at a lower rate, 34 percent, than those never married (43.5 percent). Young male turnout (38.8 percent) lags behind that of young females by 6 percentage points. Young Hispanics (20.4 percent) and blacks (44.1 percent) trail turnout of young non-Hispanic whites (48.5 percent). So the “youth vote” is not a homogeneous force. Organizing a gathering of wealthy single yuppies may pay dividends, but rallying young, minimum-wage married Hispanics might be a total waste of time, money and effort.

Heather may also underestimate the Obama factor. The Census Bureau’s historical time series shows that the 18-to-24 vote peaked at 50.9 percent in 1964, 50.4 percent in 1968, and 49.6 percent in 1972, years when charismatic figures like Barry Goldwater, Bobby Kennedy, and George McGovern energized youthful activism. Perhaps Obama will do something close to that again in 2008, but he’s got a mountain to climb to reach those records of the ’60s and ’70s.

Hill is director of Hill Research Consultants, a Texas-based firm that has polled for GOP candidates and causes since 1988.