WASHINGTON — For Karen Hughes, counselor to the president of the United States, Sept. 10, 2001, was a day of celebration and relief. It was her wedding anniversary. She and husband Jerry dined at a favorite restaurant in the Watergate and reviewed the drama and chaos of the previous months.

There’d been the long presidential campaign, the disputed election, the move to Washington. They had to move a second time when the first house didn’t work out. Then a freak summer rainstorm had flooded their basement, soaking their possessions.

All that was finally behind them. And so she could say:

“We’ve survived the worst.”

And: “Things can only get better from here.”

That Monday – call it 9/10 – was the last day of a certain kind of American innocence.

“Eye on America investigates danger in the air – hot-dog military pilots in civilian airspace,” CBS news anchor Dan Rather said in his introduction that evening.

The top story of the night: Senate investigators crack down on scams involving dietary supplements.

The nation perceived itself to be at peace, unchallenged as the world’s only superpower. There were, to be sure, bad guys lurking here and there. There were random fanatics and Unabomber types. Pennsylvania Avenue had been closed in front of the White House to prevent truck bombs like the one that hit the federal building in Oklahoma City.

At the airport, travelers were asked: Did you pack bags yourself? Has your bag been in your possession at all times?

X-ray machines at the security checkpoint were calibrated to detect a large knife or gun. A computer program flagged suspicious travelers, and their checked baggage would get extra screening. The bags wouldn’t be loaded onto the plane until the travelers had boarded the flight. The system assumed that no one would blow up a plane while flying on it.

There was a template for terror, a paradigm for how an attack would unfold. An airline hijacker would want to divert the plane to some unintended destination. Flight attendants were trained to discourage passengers from attempting heroic acts in a hijacking.

America was good at preparing for the imaginable.

Monday the 10th was the start of Acquisition and Logistics Excellence Week at the Pentagon. Secretary of Defense Donald Rumsfeld used the occasion to give a barnburner of a speech in which he declared war on the Pentagon itself – on its bureaucracy, its waste, its crusty procedures that had left the military “tangled in our anchor chain.”

Rumsfeld the reformer warned that new threats might be different from the old ones: They “arise from multiple sources, most of which are difficult to anticipate, and many of which are impossible even to know today.”

That day, five men from the Middle East, traveling in a pack, booked themselves into the Marriott Residence Inn in Herndon, Va., about 20 miles west of the Pentagon. They had reservations to fly the next morning on American Airlines Flight 77, out of nearby Dulles International Airport.

They were young, clean-shaven, well dressed. They were hiding in plain sight, one of four teams taking positions on the East Coast. There were 19 of them in all; a 20th had been turned back weeks earlier in Orlando by a Customs official because he couldn’t speak English or explain why he was coming into the country.

The five men booked on Flight 77 had stayed in cheap motels in Laurel, Md., along U.S. Route 1, close to a racetrack. They’d loitered at a pizzeria and worked out at Gold’s Gym. They’d been to Kinko’s, Giant, Safeway and Target, all within a short drive of the National Security Agency, one of the myriad government agencies charged with protecting citizens from terrorists. They’d browsed the aviation books in a used-book shop. The bookseller didn’t think twice about them.

“Just a bunch of guys,” the bookseller says.

On 9/10, ordinary Americans weren’t on the lookout for terrorists in gyms or bookstores. And what did a terrorist look like? It’s a diverse country. There are all types. Neighbors at one of the Laurel motels didn’t know what to make of the five men — didn’t know how to interpret the way they came and went in a group, the way they carried their suitcases with them at all times, the way they would hole up in the room and not watch TV or make phone calls. One neighbor later said he thought the men might be part of some kind of sex club.

Blessed by geographic isolation from the rest of the world, Americans did not feel vulnerable on their home soil. Most terror events had happened in distant places such as Lebanon, Kenya, Tanzania, Yemen.

You couldn’t get here from there.

The people paid by taxpayers to do the worrying knew better, of course. Terrorists had tried to blow up the World Trade Center in a 1993 bombing that killed six people. The 1995 National Intelligence Estimate said terrorists might strike in the United States and could target the White House, the Capitol, Wall Street and civil aviation.

In late 1999, terrorists had plotted to bomb Los Angeles International Airport at the millennium. Throughout 2001, intelligence agencies picked up chatter about something major coming down the pike.

The CIA knew that two suspected terrorists were somewhere in the country (one, it turned out, was listed in the San Diego telephone book). The FBI had detained a man who sought flying lessons in Minnesota but only wanted to learn how to steer jetliners – not take off or land. An FBI agent in Phoenix recommended that the agency scour flight schools for possible hijackers-in-training.

President George W. Bush was briefed at his Texas ranch on Aug. 6 about Osama bin Laden’s long-stated desire to strike the American homeland. The briefing document was titled, “Bin Ladin Determined to Strike in the US.” But it didn’t specify where, when or how.

A top counterterrorism official, Richard Clarke, considered issuing a broad public warning, but he had no hard facts.

“What would it say? ‘A terrorist group you had never heard of may be planning to do something somewhere’?” he wrote in his book “Against All Enemies.”

The fears did not filter down to the general public. On 9/10, what worried people most was the economy. Experts frowned at the rise in the unemployment rate to 4.9 percent. ABC News, in a report Sept. 10 about the economy, flashed a newspaper headline: “White House Sees Shrinking Budget Surplus.” The estimated federal surplus had dropped from $281 billion to $158 billion.

The president focused on his domestic agenda. On 9/10, Bush flew to Florida and gave a midday speech that highlighted his major theme of the week: Kids should read.

“It’s so much easier to watch TV and not read. And yet you learn so much more when you read,” the president said in Jacksonville. “Reading is essential. And we’ve got to get it right as a nation.”

Back in Washington, White House chief speechwriter Michael Gerson spent 9/10 working on a speech titled “Communities of Character.” It had something to do with civil engagement. It was a speech the president would never give.

“I only remember it,” Gerson says, “as the last memory of a different life.”

 Researcher Madonna Lebling contributed to this report.