Younger than most of his age cohort, he was only 14 hands (56 inches, 142 cm) high[c][8] when Windfields Farm offered all of its yearlings for sale at its annual auction.

[11] Sportswriter Jim Murray of the Los Angeles Times wrote: "Northern Dancer is the kind of colt who, if you saw him in your living room, you'd send for a trap and put cheese in it.

He was ridden by apprentice jockey Ron Turcotte, who was instructed not to use the whip but gave the colt a tap at the sixteenth pole anyway, whereupon Northern Dancer "exploded".

[12] After a brief layoff, Northern Dancer was entered in the 1+1⁄16 mile Cup and Saucer Stakes on September 28 over the Woodbine turf course, where he was assigned the top weight of 124 pounds.

Ron Turcotte was back as his jockey and took him to an early lead, but Northern Dancer tired and fell second to long-shot Grand Garcon by three-quarters of a length.

He won by 2+1⁄2 lengths, but the Daily Racing Form called him an "unwilling winner", reflecting heavy pressure from new jockey Jimmy Fitzsimmons, who used the whip throughout the stretch drive.

[12] On November 27, Northern Dancer was the odds-on favourite in a field of six horses entered in the Remsen Stakes, despite carrying top weight of 124 pounds.

[22] For his next start in the Flamingo Stakes on March 3, Northern Dancer was ridden by Hall of Fame jockey Bill Shoemaker and went off as the even-money favourite in a field of eleven.

"[12] Luro was satisfied with the performance though, feeling that the slow time of the race was the result of a fast workout a few days earlier in which Northern Dancer had fought restraint by the exercise rider.

Another horse, Allen Adair, made a run down the stretch so Hartack released his grip and Northern Dancer crossed the finish line in front by half a length.

[10] In the high pressure environment leading up to the race, Luro kept the press away from the colt, even substituting a stable pony for Northern Dancer during photo sessions.

As the field reached the track, he "bounced like a rubber ball" and gave a huge buck when the band started to play "My Old Kentucky Home".

[33] Author Kevin Chong later wrote of Northern Dancer's "short, powerful legs making like a hummingbird's wings"[34] as he ran down the stretch.

Hill Rise closed with giant strides, but Northern Dancer prevailed by a neck in a new race record of two minutes flat that stood until Secretariat broke it in 1973.

"[10] With the Preakness Stakes being run just two weeks later, Luro was concerned that Northern Dancer would find the race more demanding, especially because the track at Pimlico was deep and taxing.

[36] For the Preakness on May 16, Northern Dancer went off as the 2–1 second favourite to Hill Rise in a field of six that included the top five finishers from the Derby plus Quadrangle.

Hartack had yet to ask Northern Dancer for his run, while the jockeys of both Hill Rise and Quadrangle were working hard to maintain their position.

With Northern Dancer under a tight hold, he and Hill Rise tracked each other for the first mile behind a slow pace set by outsider Orientalist.

Bill Shoemaker on Hill Rise, who finished fourth, lodged an objection against Hartack for being squeezed off on the final turn but the stewards disallowed the claim.

"[38] In spite of the loss in the Belmont, the mayor of Toronto declared June 8, 1964, to be "Northern Dancer Day", which included a ceremony held at city hall.

Hartack relaxed his hold entering the far turn, and Northern Dancer "zoomed" past the early leaders, then drew off to win by 7+1⁄2 lengths.

[45] According to Luro, Northern Dancer had run with a splint on the inside of his left front leg since age two but had never before shown visible evidence of injury.

For his final years at stud (1985–1987), his breeding rights were privately negotiated,[59] with one season selling at auction for $1 million,[65] an amount four to five times that of his closest rivals.

[75] Combined over a period of 22 years, the top 174 Northern Dancer offspring at the Keeneland Sales sold for a total $160 million.

[97] In 2018, the city of Oshawa announced that a new elementary school, located near what used to be Windfields Farm at the corner of Northern Dancer Drive and Bridle Road, would be named after the horse.

[99] In 1990, The New York Times called Northern Dancer "the dominant progenitor of his breed" because his own success at stud was amplified by the impact of his sons around the world.

In North America, 2018 Triple Crown winner Justify has multiple crosses to Northern Dancer, in the direct male line through Storm Cat, and also through Nijinsky and Vice Regent.

[111] American Pharoah, winner of the 2015 Triple Crown is 5 × 5 inbred to Northern Dancer, through Storm Bird and El Gran Senor.

[115] According to pedigree consultant John Sparkman, 35 to 40 percent of American graded stakes winners of 2013 were male line descendants of Northern Dancer.

Notable sires that are inbred to Northern Dancer (within four generations) include Oasis Dream, Rock of Gibraltar, Hernando, Spinning World, Redoute's Choice, and Frankel.