Editor's Note: (This is an updated story first published in May 2018.)
(CNN) It's often referred to as "The most exciting two minutes in sports."
So what makes the Kentucky Derby so special?
Here are five reasons not to miss America's sporting and cultural icon, which will be held on May 4 at Churchill Downs race track in Louisville, Kentucky.
READ: Riding Derby legend Secretariat was like 'flying a fighter jet'
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It's America's longest running sports event
The first Kentucky Derby was held on May 17, 1875, when a crowd of 10,000 saw three-year-old chestnut colt Aristides, ridden by African-American jockey Oliver Lewis, triumph at Churchill Downs.
The Derby has been held at the same venue ever since, even during both World Wars and the Great Depression of the 1930s, making it the country's longest continuously held sports event.
The 145th edition of the mile-and-a-quarter race for three-year-old thoroughbreds is expected to attract more than 150,000 spectators.
The Derby is the first leg of racing's prestigious Triple Crown, which also consists of the Preakness Stakes in Baltimore and the Belmont Stakes in Belmont Park, New York.
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The Derby returns to Churchill Downs
The Kentucky Derby, first run in 1875, is the first leg of the American Triple Crown and a sporting and cultural icon in the US. It is for three-year-old thoroughbreds and is run over a mile and a quarter at Churchill Downs.
More than 150,000 racegoers packed out Churchill Downs in Louisville for last year's
Kentucky Derby, one of the best-loved events in the racing calendar.
The Kentucky Derby is one of the most anticipated annual sporting events in America.
Justify, trained by five-time Kentucky Derby winner Bob Baffert, won last year's rain-soaked event on his way to winning the prestigious Triple Crown, which also includes the Preakness Stakes and the Belmont Stakes.
The horse didn't run as a two-year-old, meaning it bucked a 136-year trend with a win in last year's race.
The event is also dubbed the "Run for the Roses" because of the garland of 554 roses draped over the winner.
The horses are randomly assigned a post position before the race. There are multiple theories to which position is best.
The event is a chance to dress up, with all manner of hats and elegant dresses on show.
The men also jump at the chance to put on their glad rags.
Famous faces regularly flock to Churchill Downs for the Derby. Here, NFL stars Tom Brady and Rob Gronkowski soak up the atmosphere in 2015. A horse named after New England Patriot's tight end Gronkowski was due to run in this year's race, but
had to pull out with a fever.
American actor Jeff Bridges (left) was in attendance in 2017.
The hats are spectacular and rival the best Royal Ascot has to offer.
In 2015, jockey Victor Espinoza rode
American Pharoah to victory -- his first win on the way to completing the Triple Crown.
It also meant Espinoza secured back-to-back victories after winning the 140th edition on California Chrome.
Punters prepare to place their bets at the wagering windows in 2014.
Trainer Bob Baffert saddled Justify to his fifth Kentucky Derby triumph in 2018. One more victory for Baffert would equal the record of Ben A Jones, set between 1938 and 1952.
It has literary history, and plenty of tradition
The Kentucky Derby has been covered by some of America's most famous writers.
In 1925, New York sports columnist Bill Corum called the Derby the "Run for the Roses" because the winning horse gets draped in a garland of hundreds of red roses.
In 1935, legendary Tennessee-born sports writer Grantland Rice described the race like this:
"Those two minutes and a second or so of derby running carry more emotional thrills, per second, than anything sport can show."
His phrase has since been shortened to describe the Derby as "the most exciting two minutes in sports" or "the greatest two minutes in sports."
Much-loved traditions include the playing of "My Old Kentucky Home" -- with the huge crowd singing along -- as the Derby horses run to the start, and the mass consumption of mint juleps, the famous bourbon-based cocktail associated with the race.
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Kentucky Derby: Fashion through the decades
As the 2016 Kentucky Derby kicks off, we take a look at some of the most eye-catching fashions through the decades.
The Derby first launched in 1875, and up until the turn of the 20th century women could be seen wearing hats, gloves, and long dresses down to their ankles.
"At any social outing in America at that time, you would have worn a hat and gloves -- and the Kentucky Derby was no different," said Chris Goodlet, Curator of Collections at the
Kentucky Derby Museum."Many women would have worn silk because of the warm weather, and be carrying a parasol."
This image features race-goers in 1926.
In the 1920s, women would also been seen wearing tailored suits. Hats and gloves were still in vogue.
Suits continued to be the outfit of choice for both men and women in the 1930s.
"In fact, in the 1930s and 1940s the formal suit seemed to be more popular than the dress,"
said the Kentucky Derby on its website.
Look closer in the top left of this 1940 image, and you'll see a race in action.
The 1950s saw women wear a more princess-style dress, with billowing skirts and fitted waists.
In the 1960s, hemlines were on the rise. Meanwhile, on the other side of the globe at Australia's Melbourne Cup, model Jean Shrimpton was causing a stir in a miniskirt that
"stopped the nation." "By the time you get to the 1960s wearing hats was no longer typical," said Goodlet.
"But the Derby keeps this tradition -- even when other social occasions don't."
Would you believe it. This couple aren't wearing hats or gloves, and the woman's dress hemline is a good few inches above her knees! Welcome to the 1970s.
In the 1980s, the bigger the better. Big hat brims, big shoulder pads, and judging by this race-goer, a big smile.
Bold prints and multi-colored suits make the 1980s a fashion decade to remember.
"In the 1970s and 1980s there was a return to the longer skirt, while the same casual attitude of the 1960s was still in place," said the
Kentucky Derby website.
"In the 1990s, the dress at the Derby continued to replace the suit, especially with younger women," added the Derby website.
"While gloves have become out of fashion, a hat never is, and the hats tend to get wilder and more expensive as the years go on."
We'll never know if their horse won. But the pink and pearls combo is a 1990s winner.
"The style in the infield is relaxed, with women wearing cool sundresses, cotton skirts, or more frequently shorts," said the
Derby website of 1990s styles.
The 21st century is here. And the tradition of race-goers making their own fantastical hats which started in the 1960s, continues to this day.
Feminine, wide-brimmed hats with a floral or feather adornment were popular in the 2010s.
A colorful crowd at the 2012 Derby.
Two years later the hats appear to have downsized.
Race-goers analyze programs at last year's Derby.
Nicknamed the "Run for the Roses" due to the blanket of roses draped on the winning jockey, the Derby has long inspired red accessories among race-goers.
And after a long day of placing bets, cheering horses, and drinking mint juleps, sometimes you just want to put your fashionable feet up.
It has legendary winners
In 1973, Secretariat won the Derby in a time of one minute, 59.4 seconds, a record that still stands to this day. By comparison, last year's race was won by Justify, ridden by jockey Mike Smith, in a time of two minutes, 4.2 seconds, in what was the wettest in the event's history, with more than 3 inches of rain.
Secretariat, also known as "Big Red," went on to clinch the Triple Crown in 1973, ending a 25-year wait.
In 2006, Barbaro captured the public's imagination with an epic Derby win followed by a heroic fight against injury. After becoming only the sixth horse to win the Derby with an unbeaten record, Barbaro looked like he could be on the way to the Triple Crown when disaster struck in the Preakness Stakes two weeks later -- he shattered his leg shortly after getting out of the starting gates.
Barbaro was put down by his owners eight months later, unable to overcome the complications he had suffered after the accident.
Justify crosses the finish line at last year's Kentucky Derby.
In 2015, American Pharoah became the first horse to win the coveted Triple Crown since Affirmed in 1978. The horse made the cover of Sports Illustrated and was photographed by US fashion magazine Vogue.
Last year, Justify became only the 13th horse to clinch the coveted Triple Crown. He was retired, unbeaten, in July, with his hall-of-fame trainer Bob Baffert saying the chestnut colt was struggling from fluid in his left front ankle. Justify retired to a lucrative stud career with $3.9 million in earnings on the track, which is not a bad return for a horse that cost $500,000.
READ: Triple Crown winner Justify retires from racing
It attracts the rich and famous
The Derby is a highlight of the social calendar and has always been a draw for the rich and famous, with some of the biggest stars in sports, fashion and Hollywood mixing with royalty.
Previous Derby guests include Britain's Princess Margaret, boxer Muhammad Ali, US presidents Lyndon B. Johnson and Richard Nixon, Hollywood legends Lana Turner and Bing Crosby, baseball star Babe Ruth and in recent years, singer Justin Timberlake, actor Jack Nicholson, Britain's Queen Elizabeth II and NFL star Eli Manning.
Singer Jennifer Nettles will perform the National Anthem in front of the famous Twin Spires of Churchill Downs this year.
Actors Jeff and Beau Bridges attended the Kentucky Derby in 2017.
The favorite tends to do well
Last year's win by Justify marked the sixth year in a row the pre-race favorite had triumphed, the longest streak since the 1890s.
This year, however, pre-race favorite Omaha Beach was ruled out late Wednesday because of a respiratory disease, making the event wide open.
Trainer Bob Baffert's Game Winner has been installed as the new 5-2 favorite at the head of the 20-runner field, ahead of stablemates Roadster and Improbable at 5-1.
The 66-year-old Baffert is aiming to equal the record of six wins set by Ben A.Jones between 1938 and 1952.
Baffert saddled Justify to the Derby and Triple Crown in 2018, three years after achieving the same feat with American Pharoah.