What is the most difficult Triple Crown to win in sports?

It's difficult enough to win a prominent championship in sports, but to triumph in more than one major event in a season or career is a far rarer feat.

Up until 2015, when American Pharoah swept the Kentucky Derby (G1), Preakness S. (G1), and Belmont S. (G1), the Triple Crown of Thoroughbred racing seemed virtually unattainable in today's landscape.

There was a 37-year drought until American Pharoah's dominant run, but one more Thoroughbred, Justify, has since galloped to Triple Crown glory.

Horse racing isn't the only sport where a Triple Crown is possible. Baseball, basketball, boxing, motor racing, Alpine skiing, and cycling also celebrate a Triple Crown — a distinction given to athletes who win or complete the three most important events in their fields.

Not all Triple Crowns are created equal, though. Let's look at four of the most notable Triple Crowns in sports — horse racing, baseball, boxing, and golf — to determine which is the most difficult to win.

In 1919, Sir Barton became the first to win the illustrious Triple Crown of Thoroughbred racing, though, he ran a far different path than horses today.

Back then, the Preakness was 1 1/8 miles, as opposed to today's length of 1 3/16. The Belmont was also shorter, at 1 3/8 miles, compared to the current distance of 1 1/2 miles.

It wasn't until Gallant Fox's dominance in 1930 that the moniker "Triple Crown" became commonplace in horse racing. Between 1930 and 1948, seven horses earned the title, then the sport endured a 25-year drought.

Secretariat put an end to the dry spell in 1973, as the esteemed chestnut colt set records in all three races. Seattle Slew (1977) and Affirmed (1978) etched their names into history soon after, but an even longer Triple Crown drought emerged after the late 1970s.

Since 1875, when the Kentucky Derby ran its inaugural race, only 13 horses have crossed the finish line first in each of the Derby, Preakness, and Belmont.

As of 2021, 23 horses have triumphed in the Derby and Preakness but fell short in the Belmont, while 29 horses have won two of three Triple Crown races in a different order.

There are myriad theories as to why the Triple Crown of racing is so difficult to achieve. For one, the three races take place over the course of five weeks, starting with the Derby on the first Saturday in May and ending with the Belmont, on the first or second weekend of June.

Not only do horses get little rest between each race, but they are asked to rely on a different set of skills at different distances.

The winning Thoroughbred in the Derby will almost always face new competition in the Preakness or Belmont, against horses who come in fresh.

Breeding and training priorities have also changed. As Secretariat's owner and breeder, Penny Chenery, once explained, "We breed horses to be early winners. … We don't train them the same way. ... In my day, we raced every other week. And it just built the strength and allowed the horse to mature before you asked the ultimate question."

The opportunity for a Triple Crown has already been eliminated in 2021, as Medina Spirit crossed the wire first in the Kentucky Derby but was bested by Rombauer in the Preakness.

In MLB, there are two Triple Crown titles a player can obtain, by leading either the American League or National League in three specific statistical categories in the same season.

The Triple Crown of batting is earned by recording the highest batting average, home run total, and RBIs in a single season. It has been accomplished 17 times but just once —  by Miguel Cabrera (2012) — since 1967.

The three statistical categories in the Triple Crown of pitching — wins, strikeouts, and ERA — are more complementary. This Triple Crown is a bit more common, and has occurred 39 times, including six times since 2000.

Last season, Shane Bieber of the Cleveland Indians topped the AL in wins (eight), strikeouts (122), and ERA (1.63), during a season shortened to 60 games because of the COVID-19 pandemic. 

Before Bieber, Justin Verlander and Clayton Kershaw attained the Triple Crown in 2011.

The Triple Crown of boxing was once an exceptional achievement that has become far more ordinary, with the advent of additional weight classes and sanctioning bodies from which a boxer can earn a "world" championship. 

To claim a Triple Crown in boxing, an athlete must secure titles in three different weight classes throughout their career.

Bob Fitzsimmons became boxing's first triple champion when he won the middleweight, heavyweight, and light heavyweight titles, between 1894 and 1903.

Only nine male boxers and one female (Amanda Serrano) have obtained three different division titles in one of the original eight weight classes — flyweight (112 pounds), bantamweight (118), featherweight (126), lightweight (135), welterweight (147), middleweight (160), light heavyweight (175), and heavyweight (200 or more).

The list of triple champions is substantial (52), if you expand the criteria to boxers with titles in one of the 17 recognized weight classes from one of the major boxing entities (WBA, WBC, IBF, WBO, and The Ring).

The most difficult Triple Crown to acquire is in golf, where a player must win three of four major championships in the same year.

The feat has been witnessed just twice — in 1953, when Ben Hogan won the Masters, U.S. Open, and the Open Championship in the same year, and in 2000, when Tiger Woods won the U.S. Open, the Open Championship, and PGA Championship.

Even more rare is golf's Grand Slam, in which a player finishes first in all four majors in one season. That only happened in 1930, when Bobby Jones collected titles at the four majors of his era — the Amateur Championship, U.S. Amateur, U.S. Open, and Open Championship.

One reason golf's Triple Crown is nearly impossible to pull off is that three of the current four majors (PGA Championship, U.S. Open, and Open Championship) change courses each season.

Only the Masters has a permanent home at Augusta National, and conquering that course requires a skill set that sometimes does not translate to the other three major courses in the same season.

Woods is the greatest golfer not named Jack Nicklaus, and won, at most, two majors in one season three times after his Triple Crown triumph in 2000.

Most recently, Brooks Koepka won two majors in the same year, at the U.S. Open and PGA Championship in 2018. However, he did not play in the Masters that year, and he tied for 39th at the Open Championship.

Jordan Spieth came the closest to a Triple Crown in the past decade, when he won the Masters and U.S. Open in 2015, then tied for second at the PGA Championship and fourth at the Open Championship.

With so much variance in course layout and field competitiveness at each major, on top of the already difficult nature of this mental sport, the Triple Crown of golf is, undoubtedly, the hardest to obtain.

We've been fortunate to witness a number of Triple Crowns in sports in the past century, but golf's Triple Crown is one we probably will not see again in our lifetime.