In the midst of the campaign month of October came the news last week that the population of the United States has passed the 300 million mark. There's a sharp contrast between the negativity of the political climate and the robustness of our demographic increase -- we were at 200 million in 1967, less than four decades ago.

Then, as now, Americans were in a negative mood, but had much more to be depressed about. We were then mired in a war that produced more than 20 times the number of American deaths as the conflict in Iraq has so far. We were in the midst of the Cold War, with its ever-present threat of nuclear annihilation, and the bipartisan Cold War consensus was about to break down. Our cities were ablaze in race riots, and our economy was about to enter an era of stagflation -- low growth and high inflation.

Now, most things are demonstrably better. As I noted last summer, levels of warfare around the world have reached a historic low, so that even the loss of one American life in Iraq can land on the front page. The world economy is growing as never before, with millions of people rising out of poverty every year. The American economy continues to surge ahead.

Since 1983, we have lived through just two brief recessions, one at the beginning of each decade, and otherwise have had low inflation and steady economic growth. Crime and welfare dependency have been approximately halved in the past 15 years. Our air and water are much cleaner than they were when there were 100 million fewer of us. Our life expectancies are longer.

Why so cranky? So why do large majorities of voters say the nation is off on the wrong track? One reason is that we have come to expect good things. Even as consumers keep spending lots of money, they get cranky when gas prices spike upward -- and then don't take much note when, presto, the market works and they plunge back down again. We take it for granted that Times Square is as crime free a tourist zone as Walt Disney World. We are dismayed by continuing violence in Iraq because we have come to expect military interventions to be as casualty free as our effort in Kosovo.

But there is something else. It's the looming threat behind the headlines: London terrorist bombers arrested. Terrorist plot to bomb trains in Germany. Iran is developing nuclear weapons, while its president denies the Holocaust and threatens to destroy Israel. Hugo Chavez at the United Nations railing at the United States. North Korea is developing nuclear weapons to go with the missiles it already has. All these remind us that there are people out there who want to destroy our bounteous and tolerant civilization. And we know, since Sept. 11, 2001, that they will inflict any damage they can. North Korea is a proven weapons proliferator. Iran is the world's leading state sponsor of terrorism. It's not hard to imagine them equipping terrorists with nuclear weapons -- or with the biological weapons (anthrax, plague) North Korea is said to be developing. Remember the anthrax attacks of September 2001? It turns out we still have no idea where the anthrax came from.

"History is a nightmare from which I am trying to awake," the novelist James Joyce once wrote. From the fall of the Berlin Wall and the collapse of the Soviet Union up until the morning of Sept. 11, 2001, we were on a holiday from history. We were happy to pay little attention to the Islamofascist terrorist threat that should have been apparent from the first World Trade Center bombing in 1993. We left that to government officials, who took it seriously and did some things to address it -- but in hindsight not enough. Since then, we took the offensive and have had some successes in stopping terrorists. But we seem to be growing tired of the fight.

Now it appears that voters are willing to turn over Congress to a party most of whose representatives voted against allowing the National Security Agency to surveil without a court order al-Qaida suspects when they place calls to persons in the United States and against allowing terrorist interrogations under rules supported by John McCain. We are weary, it seems, and ready to go back on holiday. Some things -- a nuclear attack on the United States, the successful release of a disease pathogen that could kill millions -- are just too horrifying to think about. But maybe we should think more about them. As Leon Trotsky is supposed to have said, "You may not be interested in war, but war is interested in you."