“Wow.”

This single word, quietly uttered by track announcer Phil Georgeff of Arlington Park, perfectly summed up the feelings of disbelief in the moments following Dr. Fager’s win in the 1968 Washington Park Handicap. Carrying 134 pounds and facing a talented field of rivals, Dr. Fager had prevailed with astonishing ease, effortlessly pulling away in the homestretch to win by 10 lengths without any urging from jockey Braulio Baeza. It was a breathtaking performance.

He had also run the one-mile race in 1:32 1/5, shattering the American record for a mile on dirt.

Historically, the distance of one mile has been considered the truest test of a Thoroughbred’s talent. To excel at a mile, a horse needs the speed of a sprinter, but also the stamina to carry that speed beyond the typical sprint distance of three-quarters of a mile.

Throughout the history of racing, the American record for a mile has changed hands many times, being repeatedly established and broken by some of the sport’s most legendary horses. A century ago, back when racetracks weren’t as fast as they are today, the record for a mile on dirt was officially held by Sun Briar, a two-time champion who posted a mile in 1:36 1/5 at Saratoga in 1918.

But faster clockings weren’t inconceivable—the great Salvator had gone a mile in 1:35 ½ during a special race against time in 1890, in which he benefited from a super-fast straight track, a running start, and a couple of pacemakers. Furthermore, the seemingly ageless Roamer—Horse of the Year in 1914—would post a time of 1:34 4/5 at Saratoga in 1918, once again in a race against time.

Outside of these special events, the official race-record time dropped much more gradually. The legendary Man o’ War became the first to run a sub-1:36 mile under real race conditions when he clocked 1:35 4/5 while winning the 1920 Withers Stakes at Belmont Park. This marked the beginning of a streak when Belmont was the place to be for breaking records, for the next three record holders for the mile—Audacious (1:35 3/5 in 1923), Cherry Pie (1:35 2/5) in 1923) and Jack High (1:35 flat in 1930)—would all achieve their record-breaking success at Belmont.

With the mark being lowered to 1:35, it was only a matter of time before someone joined Roamer with an official sub-1:35 clocking, and that honor went to Equipoise, a two-time Horse of the Year and four-time divisional champion. Nicknamed “the Chocolate Soldier,” Equipoise was hailed as one of the best horses ever seen on the American turf, and by winning a 1932 handicap race at Arlington Park in the scintillating time of 1:34 2/5, he simultaneously shattered the record for the fastest mile in an actual race and also Roamer’s long-standing record against time, eliminating any confusion stemming from having multiple records under differing circumstances.

From that point on, the “American Record Mile Club” would limit membership to an exclusive group of future Hall of Famers. Equipoise’s record would hold up for 17 years before Coaltown, in the midst of a Horse of the Year campaign, dropped it to 1:34 flat during an easy win in the 1949 Whirlaway Handicap at Washington Park. But Coaltown’s reign lasted less than a year before his Triple Crown-winning stablemate Citation—back from a year off due to injury—stunned the racing world with a mile in 1:33 3/5 at Golden Gate Fields, despite the fact that he was clearly short of his peak form!

The great Swaps made a habit of breaking track and American records during his 1956 Horse of the Year season, and Citation’s record would be among the ones to fall. Over a fast track at Hollywood Park, Swaps cruised through a mile in 1:33 1/5 in the Argonaut Handicap, a race in which runner-up Bobby Brocato—beaten just 1 ½ lengths—likely broke Citation’s record as well.

Over the next decade, Swaps’ time would be equaled twice, but it was not surpassed until Buckpasser came along. During a sensational 3-year-old season in 1966 that saw him win 13 of his 14 starts, Buckpasser blew Swaps’ record away in the Arlington Classic Handicap at Arlington Park, rallying powerfully into a fast pace to stop the clock in 1:32 3/5, becoming the first horse in history to shade 1:33.

Two years later came Dr. Fager’s tour-de-force victory in the Washington Park Handicap, at which point a sub-1:32 mile on dirt must have seemed not only within the realm of possibility, but a near certainty to occur within the next 10 or 15 years.

Instead, the records stopped coming. In 50 years, the American record for a mile had been lowered four seconds from 1:36 1/5 to 1:32 1/5; had the trend continued, we would be seeing miles in 1:28 1/5 today.

But by clocking a mile in 1:32 1/5, Dr. Fager seemingly raised the bar out of reach. Nearly 50 years have passed since Dr. Fager elicited a “wow” for the ease of his record-breaking run, yet his record still stands as the untouchable, unbreakable standard for a mile on dirt. The champion Easy Goer came close to equaling it, posting a time of 1:32 2/5 while winning the Grade 2 Gotham Stakes in 1989. And in 2003, a colt named Najran came tantalizingly close to eclipsing Dr. Fager’s record, going a mile in 1:32.24—just 0.04 slower—while winning the Grade 3 Westchester Handicap.

Yet “close but not quite” isn’t enough. Perhaps the only horse that could have bettered Dr. Fager’s record was Dr. Fager himself, for much of the talk after his record-breaking run centered on how fast he might have run if urged to the finish. So great was the performance that “Baeza took his time sauntering Dr. Fager back to the winner’s circle … and the crowd made the most of it,” wrote Cooper Rollow in the Aug. 25, 1968, edition of the Chicago Tribune. “Even the holders of tickets on the losers stood and applauded as the great champion passed the stands. Seldom has any sport crowd recorded as fine an ovation to a winner.”

If only the crowd could have known that half a century later, that horse—that moment—would still stand as the pinnacle of speed and stamina from a Thoroughbred racehorse.