Talk about getting a swollen head: When it comes to consuming helium, Macy's is second only to the federal government, and it's all on account of Big Bird, Garfield and other balloon stars.

It will take 400,000 cubic feet of helium to inflate the 16 giant balloons and other attractions featured in this year's Macy's Thanksgiving Parade.

The new cast of giant balloons features a 62-foot-tall SpongeBob SquarePants as well as an extra-large Chicken Little, who will require 50 wranglers to keep him from flying the coop.

The M&M characters have also been balloonified for the first time. The red and yellow corporate mascots have forgone their usual chocolate filling for 13,335 cubic feet of helium as part of a 50-foot attraction.

The 78th annual Macy's Thanksgiving Day Parade kicks off at 9 a.m. Thursday, marching 2 1/2 miles down Manhattan, from West 77th street, through Columbus Circle and down Broadway to -- where else? -- Macy's flagship department store at Herald Square.

Marching bands from all over the country, floats celebrating everything from Barbie to the Weebles, not to mention stars such as Hilary Duff and American Idols Ruben Studdard and Clay Aiken, will be joining in on the fun.

But it's hard to eclipse the shear magnitude of the giant balloons. The beak alone on Big Bird is 13 feet long.

These balloons -- once rubber, now polyurethane -- have been a Thanksgiving tradition since the earliest years of the parade, but they remain a source of wonder.

If you're watching this event with a kid -- and that's the best way to watch any parade -- here's a handy timeline that just might help explain how America's most famous parade took off, what happens to old balloons when it's time to retire, and what keeps these airborne behemoths from spinning out of control.

1924: Lions and Tigers and Clowns, Oh My
In the first parade, horse-drawn floats carried real lions and tigers through Manhattan. Macy's employees marched through the streets dressed up as cowboys, clowns, Arab sheiks and knights in armor. On the last float -- where you can still find him -- rode Santa.

Back in 1924, Macy's never imagined that its holiday parade -- originally dubbed the Macy's Christmas Parade -- would be anything more than a holiday party for its staff. Crowds lined the streets, however, and that's when management saw its potential to kick off the holiday shopping season.

To avoid confusion, Macy's changed the parade's name. Santa remained the star, but the wild animals scared some kids. That's bad for business. What attraction could please everybody? How about giant, colorful balloons shaped like animals?

Thus, Felix the Cat -- and eventually Mickey Mouse and Garfield -- replaced critters from the Central Park Zoo to become America's ultimate party animals.

1927: Up, Up, and Away in an Exploding Balloon
The first parade balloons were filled with air and carried through the streets. Then, in 1927, helium came along, and it was an instant sensation, giving the world, among other things, the first 50-foot inflatable hummingbird.

At the parade's finale, someone had a really novel idea -- what if the giant balloons got to go free? Parade organizers decided to liberate 10 balloons into the skyways.

Unfortunately, helium expands with altitude. One by one, four of the balloons exploded -- even before they could pass the top of the Empire State Building. Among the casualties: a 21-foot toy soldier.

1928: Catch a Balloon, Win a Prize
In 1928, valves were added to the balloons so that they could float above the city without popping. Macy's decided to turn the event into a contest -- by offering $50 rewards for each balloon returned to the store.

The great balloon hunt quickly turned ugly, however. In the first year, a massive dachshund balloon landed in the East River, and two tug boats rushed to be the first to retrieve it. In the process they completely destroyed the overgrown puppy.

Other balloons, found at least 100 miles away, came back to the store riddled with bullets, apparently shot from the sky by eager bounty hunters.

In 1931, an eager airplane pilot hooked a balloon with a toe rope. Felix the Cat went splat against the plane's wing, and Macy's sent out a proclamation disqualifying aviators. But even that didn't stop another pilot from nearly going into a tailspin over Long Island, trying to retrieve a balloon.

From then on, old balloons found a new resting home -- in deep storage.

1934: Cartoon Stars Get Balloon Makeovers
By the mid-1930s, nearly every cartoon star was getting balloonified. Walt Disney personally oversaw the building of a 40-foot Mickey Mouse. Donald Duck came a year later, with Popeye soon to follow.

In a sure sign that Hollywood had acknowledged the marketing potential of the parade, the Tin Man appeared as a 70-foot balloon in 1939, while "The Wizard of Oz" was still in theaters.

The same balloon used for the Tin Man was repainted in a green and yellow suit, turning him into "Laffo the Clown."

1942: Uncle Sam Saves Our Hide (With His)
When World War II started, the parade was put on hold for three years. In a demonstration of patriotism, Macy's executives ceremoniously chopped up several giant balloons and presented the rubber remains to New York Mayor Fiorello LaGuardia to help in the war effort.

Uncle Sam was among those who made the ultimate sacrifice. In 1941, a year before he gave his rubber life for his country, the red, white and blue behemoth stood 75 high, bestriding Times Square. In an ominous sign of the tough times ahead, Uncle Same began to leak that year, prompting the Herald Tribune to report, "Uncle Sam Springs a deficit."

Just 10 days later, Japan bombed Pearl Harbor.

1946: A Miracle on 34th Street
Santa Claus gave the Macy's Thanksgiving Parade it's biggest gift -- turning it into a national parade. The parade figures prominently in "Miracle on 34th St," the instant Christmas classic about a department store Santa who is convinced he's the real thing.

In a scene filmed in an apartment on New York's Central Park West while the 1946 parade was in progress, the teddy bear, Pilgrim and baseball player balloons float by a window, while actor John Payne is talking with actress Maureen O'Hara and a young Natalie Woods.

Footage of the 1946 parade was so popular with moviegoers that NBC took the bold step of giving the New York event a national broadcast. It quickly evolved into a perennial ratings winner, regularly watched by more than 45 million TV viewers.

1956: Not So Mighty Mouse
As the parade became a national affair with a large TV following, minor slip-ups became more apparent. In 1956, Mighty Mouse couldn't fight 45-mph winds and collapsed in a heap.

Three years earlier, Little Bo Peep not only lost her sheep, she missed her float. Oscar-winning Actress Celeste Holm, best known for her work in "All About Eve," had to make a mid-parade arrival by motorcycle.

A helium shortage in 1958 seriously threatened the parade. Macy's responded, however, by suspending the floats on cranes.

1963: Kennedy Assassination
The 1963 parade would have been canceled if not for the go-ahead from the highest office in the land. John F. Kennedy had been assassinated, and the parade was scheduled to take place just three days after the funeral.

Lyndon Johnson, the newly sworn-in president, actually urged Macy's to go through with the parade, even with the nation still in mourning. Every flag bore seven feet of black bunting, as an 80-foot rendition of Bullwinkle saluted America as a lovable moose who feels your pain.

1997: Balloons Run Amok
Throughout the parade's history, reports of errant giant balloons usually brought a smile. The Santa Claus balloon burst at the seams in 1941, apparently because balloon handlers wanted to make Father Christmas extra jolly and plump.

A few years earlier, New Yorkers were regaling each other with tales of another balloon, known as Father Knickerbocker, who got his big nose stuck in the elevated train line at Lincoln Square.

In 1985, rains left the Kermit the Frog balloon so waterlogged that handlers had to carry the big green guy down the street.

But in 1997, balloon control was no laughing matter. With winds gusting at 30 mph, Sonic the Hedgehog lost his head. The Nestle's Quik Bunny lost an ear near Columbus Circle. Police had to cut the tail off The Pink Panther to keep him under control.

The Cat in the Hat crashed into a lamppost, knocking debris into a crowd on 72nd Street and injuring several people, including one woman who suffered a fractured skull and was in a coma for nearly a month.

In the aftermath, New York City imposed stricter guidelines. The parade would no longer allow balloons more than 70 feet tall, 40 feet wide or 78 feet long, forcing Woody Woodpecker, among others, into retirement.

City officials also ordered that balloons be grounded if the wind goes above 23 mph.

2001: After Sept. 11
After the Sept. 11 attack, the Macy's Thanksgiving Parade once again had to question if it could go on. The fate of the World Trade Center had led many to question the safety of New York City, but officials vowed to heighten security, and more than 2 million people eventually showed up.

To honor the more than 350 police and firefighters who died when the twin towers collapsed, the parade was headed by a troop of children of New York City firefighters and policemen.

The balloons also did their part. Harold the Fireman, a 32-foot balloon originally seen in the 1948 parade, returned, ready for action, and his fireman's cap was altered to indicate that he was a New York City firefighter.

This same float had appeared many times in the parade, after many serious balloon makeovers. In 1945, Harold was a clown. In 1946, he was a baseball player -- and even had a bit part in "Miracle on 34th Street." A year later, Harold was a policeman.

But in 2001, Harold was up there with Santa Claus when it came to getting applause.

And now, as the 2004 parade gets under way, Harold is one of the returning veterans. This year, he may take a back seat to SpongeBob SquarePants, but it's good to know he's still out there.

(from ABC News)