Here’s a new element to factor into your calculations about the 2004 election: The turnout is likely to be the highest in a generation.

That’s because, unlike other elections when the nation was at peace abroad and at peace with itself, this is a country in turmoil. It is at war in two theaters, its economy is unsettled, its sense of security is rattled, and its instinct for consensus is disrupted.

Four years ago the election seemed like an irritating distraction for a nation that was at peace and enjoying a sense of prosperity. There was no great urgency, no great issue. That’s not true today. Troops are fighting in Afghanistan and Iraq, national leaders speak openly about the threat of terrorist attacks, and Americans are worrying about jobs and the economy.

So there’s nothing wrong with your television set; this is an unusually contentious period, with unusually important issues: How is national security defined, and how is it protected? What freedoms are inviolable, and should some rights be curbed in order to preserve freedom? In what cases should the United States make pre-emptive strikes against other nations? Is the country experiencing an economic revival, and in what ways is this recovery different from other recoveries?

The nation faced several important issues in 1976, only two years after the Watergate scandal prompted the only presidential resignation in history and only a year after the communists took over Vietnam. In August of that year, polls showed that 45 percent of the nation thought it really mattered who won the election between President Gerald R. Ford and Gov. Jimmy Carter. This spring, 63 percent of the nation feels that the election really matters.

That’s a huge difference, symbolic of a huge difference in the stakes in this election.

The sense that the 2004 election isn’t an ordinary contest grows out of two factors — all those issues that are in play plus the polarization that the nation feels.

Many commentators argue that the polarization is a reflection of the divisions between Democrats and Republicans in Washington, the fact that the 2000 election was a statistical tie and the notion that the GOP’s margins of control in the House and the Senate are infinitesimal.

I don’t think that’s correct. It’s possible, for example, that small margins of partisan advantage could mean not division but consensus. But that’s not the case in the capital or in the country.

There are real disagreements on issues cultural (abortion), political (civil liberties) and economic (taxes). And there are real differences in how Republicans and Democrats view President Bush. And real differences on issues of war and peace.

Not one of these differences grows out of tensions from the overtime election of 2000. Indeed, President Bush’s term began with awkwardness but with goodwill on both sides of the aisle. No more.

“This is an unusual election,” says Andrew Kohut, the director of the Pew Research Center for the People and the Press. “There’s a new threat to America, and the polarization in the country is about how to respond to it. Democrats had been giving Bush the benefit of the doubt in the early days, and then there was the great national unity after Sept. 11. But it came apart, mostly because of Iraq and over differences about homeland security and civil liberties.”

Polarization is hardly a new phenomenon; the country was polarized after the first term of Franklin D. Roosevelt. In fact, the big jump in voter participation in the 1930s came not in 1932, when the country was still in shock over the onset of the Great Depression, but in 1936, when the country had a chance to evaluate how FDR responded to that challenge.

Similarly, a big jump in voter participation very likely will occur later this year, when the country — divided as Americans were in 1936 — approaches a verdict on President Bush’s response to terrorism and economic distress.

Some experts believe the spike in voter turnout in 2004 will be far bigger than the 5 percentage-point jump of 1992, when the combination of a struggling economy and the presence of an unusual political force, billionaire Ross Perot, brought new voters to the polls.

“Some elections can pull people back to the voting booth,” says Thomas Patterson, a political scientist at Harvard’s Kennedy School of Government who has studied voter participation patterns. “We know that. But we don’t know whether we can keep them in the voting booth.”

That’s a big worry. Curtis Gans, who heads the Committee for the Study of the American Electorate, thinks that the gains expected in 2004 will evaporate once the current crises abate.

“This is a big election with big issues,” says Gans. “But it’s a temporary rise, because none of the issues governing civic disengagement have been addressed. We’ve had a generation of politicians who have betrayed trust.”

Even so, the public seems far more interested in politics this time around, and with good reason. The Pew poll shows that 65 percent of the public says it has thought “quite a lot” about the election. At this point in the election cycle four years ago, only 48 percent could say that. Memo to Messrs. Bush and Kerry: You have a captive audience out here. Use it wisely.

David Shribman is a columnist for Universal Press Syndicate.