Five-ring Circus

Katie Ledecky vs. Secretariat

Which machine was more tremendous?

Katie Ledecky winning the women’s 800-meter freestyle was the biggest lock of the Rio Games. The only two things in question on Friday night: how much time Ledecky would chip off her own world record, and how badly everyone else would get dusted.

After 50 meters, Ledecky was already ahead of the field by 0.85 seconds. She increased her lead to almost 2 seconds after 100 meters, and to more than 2.5 seconds after 200 meters. At the 400-meter mark, she led by 5.49 seconds. At 600 meters, the margin had grown to 8.56 seconds. In the end, Ledecky touched the wall in 8:04.79, smashing the world record she’d set back in January by 1.89 seconds. The second-place finisher, Great Britain’s Jazz Carlin, finished 11.38 seconds behind the 19-year-old American. Here is some visual proof that this was a very, very big lead.

Katie Ledecky of the United States leads the field in the women’s 800-meter freestyle final at the 2016 Olympic Games on August 12, 2016.

Photo by Adam Pretty/Getty Images

After the race, everyone on Twitter made the same observation:

FiveThirtyEight’s Benjamin Morris had actually made the comparison on the eve of the Rio Olympics, noting that “the more [Ledecky] swims, the more she separates from the field.” Katie Ledecky, Morris wrote, “is pretty much the Secretariat of swimming.”

So, who did it better, the greatest horse of all time or the best distance swimmer in history? Watch the video at the top of the page and judge for yourself.

Now, let’s look at what the numbers say. In 1973, Secretariat won the Belmont Stakes by 31 lengths. The American Thoroughbred was “moving like a tremendous machine” in the words of announcer Chic Anderson. How tremendous? Secretariat set an American record that’s yet to be broken, running a mile and a half on dirt in 2 minutes, 24 seconds. One horse length is equal to roughly eight feet, so Secretariat won the Belmont—a 7,920-foot, or 2,414-meter, race—by approximately 248 feet, or 75.6 meters.

As stated above, Ledecky won the 800-meter freestyle at the 2016 Olympics by 11.38 seconds. Silver medalist Jazz Carlin swam her last 50 meters in 29.40 seconds, meaning she was traveling at 1.7 meters per second as she approached the finish. That means Carlin was roughly 19.4 meters behind Ledecky when the American touched the wall. Secretariat’s race was three times longer than Ledecky’s—2,414 meters compared to 800—and his margin of victory was roughly four times larger. Advantage horse.

There are several key things to note here. First, Secretariat was galloping over the dirt at Belmont Park at 37.5 miles per hour; Ledecky was churning through the water in Rio de Janeiro’s Olympic Aquatics Stadium at about 3.7 miles per hour. Second, Secretariat had just four opponents in the 1973 Belmont compared to Ledecky’s seven in Rio. Third, the 1,500-meter freestyle, which is unfortunately not a part of the Olympic program, is probably Ledecky’s best event; at the 2015 world championships, she set a world record and beat the field by about 24 meters. Fourth, Ledecky is just 19 years old. You think she looks like Secretariat now? Wait until she grows up. Fifth, Secretariat is a horse and Ledecky is not, and this whole exercise is pretty ridiculous. Sixth, Secretariat did not win a single Olympic medal. At the Rio Olympics, Katie Ledecky won five, four of them gold. Take that, horse.

See more of Slate’s Olympics coverage.