On July 4, watchful revelry

Amid a slew of vague warnings about possible terror attacks, the nation is readying for its first Fourth of July since 9/11.

Patriotism is swirling in the air. So are F-16 fighter jets: Combat air patrols over key cities have been revived for the holiday.

Freedom is on people's minds. And in Boston, anyway, colorful security bands will be on the wrists of thousands of revelers – to prove that they have cleared key checkpoints, some with metal detectors.

In the skies over Washington and other cities, a new fireworks display called "The American Tribute" will debut: First a big burst of red, then silence, then a burst of white, then silence, then a burst of blue. On the ground at the National Mall, meanwhile, miles of rust-red snow fences – and 2,500 security officers – will restrict partygoers' movements.

In all, it may be the most armor-clad, security-conscious Independence Day in American history.

Yet despite all the July 4th jitters, many citizens seem downright determined to profess their patriotism outside and in public in gathered masses. Officials at mega-bashes in Boston, New York, and elsewhere expect big-as-ever crowds. And, in what may be an emerging trend, organizers of small-town events predict new influxes, too. These lower-security, less-crowded festivals – with three-legged races, face painting, and the like – seem to have new resonance after 9/11.

"We're not in a panic, but there is a sense that people are taking a deep breath and going out to play," says pollster John Zogby.

Take Jim Rowland, a Washington-area computer consultant who has come to the Mall on July 4 for years. "Yeah, it's intimidating," he says of new security measures and the threat of attack, but adds: "I don't respond to vague threats – only concrete ones." He'll be on the Mall "for sure."

A friend of his, Kim Koons, laughs a tad nervously at what she calls Mr. Rowland's "What, me worry?" approach. "It is a pretty fine opportunity" for terrorists to make a big impact, says the National Archives employee. She's not alone: In one poll, 57 percent of Americans said an attack is at least "somewhat likely" during the holiday.

Yet Ms. Koons, like many Americans, appears ready to overcome – or ignore – her fears. She'll probably go to the Mall.

If so, she'll encounter a whole new security regime. The Mall's nearest Metro stop – which 91,000 people used last year on the 4th – will be closed. Bomb-sniffing dogs will be on patrol. Revelers can't bring coolers or other big items. And every object and person at the usually wide-open Mall will be checked at 35 entrances by police with magnetic-wands. Concerned about bridge bombings, authorities have told boaters on the Potomac not to float under overpasses.

The most visible security measure is the parallel set of snow fences – about 10 yards apart – snaking around the Mall. Officers will stand between the fences to ensure unscreened people don't sneak in. Some wonder if the fences will do much good. "If someone's going to do something, I don't know if a little fence is going to stop them," says Martin Gould, a Park Service employee helping set up the fencing.

Indeed, experts distinguish between feel-good measures and ones that actually work. "A large presence of security personnel is the single best thing to provide the feeling of security," says risk-management expert John Fannin. It's doesn't necessarily thwart attacks. "It's not likely that terrorists will come marching through the barricades," he says.

More useful, experts say, are ID checks, unified command centers to help law-enforcement agencies work together, overhead surveillance, and preemptive intelligence.

In other cities, preparations continue. For Boston's big party, just 8,000 of the expected 400,000 revelers will get wristbands – enabling them to get close to the the main concert stage. Police helicopters will beam live video back to the unified command center.

At "Fair St. Louis," officials have struggled with false news reports – including that the fireworks display was canceled for security reasons. (It hasn't been.)

In New York, Mayor Michael Bloomberg told celebrants to "relax and let our law enforcement professionals do the worrying for you."

But experts suggest that revelers can feel a sense of safety if they keep a sharp eye on whether barricades are in place, IDs are being checked, and security patrols are ongoing. They also recommend identifying an evacuation route.

Recent jitters were sparked by a series of mostly vague government warnings. And two specific concerns – a threat against Las Vegas and reports that a boatload of Al Qaeda members was spotted off California – were discounted. But last week, the FBI quietly warned law-enforcement agencies that even though it had no credible tips about attacks, the significance of the date "warrants increased vigilance."

Indeed, there is at least some history of Al Qaeda striking on symbolic dates. The East Africa embassy bombings on Aug. 7, 1998, came on the anniversary of US troops landing in Saudi Arabia during Desert Shield in 1990. But most other Al Qaeda attacks – including 9/11 – were on apparently random days.

Domestic terrorists also have a history of striking on key dates – or at high-profile venues. Timothy McVeigh's Oklahoma City bomb exploded April 19, the same date the siege at Waco, Texas, ended – and the Revolutionary War began. An American, Eric Rudolph, is the prime suspect in the high-profile 2000 Atlanta Olympics bombing.

The worry about big events being hit may push some people toward smaller celebrations. In Kent, Wash., 30 miles from Seattle, they're expecting more people than usual for the gunny-sack races, pie-eating contest, and balloon toss.

"I'm hearing people are tired of the traffic and the fuss down in Seattle," says organizer Mark Hendrickson. The security apparatus will consist of 10 to 15 police officers and a new 900 megahertz radio system "so we can talk to each other throughout the city," says Mr. Hendrickson.

In Leesburg, Va., organizers expect far more than the usual 20,000 people. Revelers will find Uncle and Mrs. Sam strolling the grounds, "bounce houses," and old-fashioned carnival games. The fireworks display will cost $25,000. (Washington's will be $110,000.) "Ours is one of the better fireworks shows in Loudon County," boasts organizer Abby Kimble, adding with a wink of small-town modesty, "If I were to say it was the best one, I'd be bragging."

• Stella Lee in New York contributed to this report.