On August 12, 1938, the Del Mar Thoroughbred Club hosted a $25,000 winner-take-all match race between Charles S. Howard's Seabiscuit and the Binglin Stable's colt, Ligaroti.

In front of a record crowd that helped make Del Mar race track a success, Seabiscuit won by a nose.

Initially, the grounds were used for training by the United States Marine Corps, then as a manufacturing site for parts to B-17 bombers.

In the 1980s, the infield was opened to spectators and in 1984 Trevor Denman became the voice of Del Mar and in the 1990s, the track underwent a major renovation.

They focused Del Mar as a fashionable destination, using social media and other avenues to market the racetrack.

They also hired jockey and model Chantal Sutherland to be the new face of the Del Mar Thoroughbred Club.

[12] One of the largest draws each year for the Del Mar Racetrack has become Opening Day with its hats contest and parties.

The work included widening the course to 80 feet and softening the curve coming out of the diagonal chute, thus allowing more horses to compete in turf races.

[16] The following year, Del Mar renovated the main track, installing El Segundo Sand.

Starting in 2014, Del Mar began to run more racing cards due to the closure of the Hollywood Park Racetrack.

Larry Collmus temporarily replaced Denman as Voice of Del Mar after 36 years for the summer meet.

Denman did return for the fall meet in November,[citation needed] and resumed calling the Del Mar races in July 2021.

[20] Similar to the meet in 2020, around the COVID pandemic period, it was decided that the KAABOO festival would also be relocated from the Padres to their original place in the Del Mar Fairgrounds.

Mark Terry with FLAAC said “it made sense to bring [KAABOO] back to its inaugural home where it had performed so well.”  “Its official: KAABOO music festival returning to Del Mar Fairgrounds in September 2024.” from San Diego Union Tribune also states that the “Board members for the 22nd District Agricultural Association, which runs the fairgrounds, approved the deal with Festival Licensing and Acquisition Corp.” KAABOO music festivals change of location was signed Tuesday and will take action in September of 2024.

[23][24] Del Mar Fairgrounds features six exhibit halls totalling 219,380 square feet (20,381 m2) of space.

[25] During peak demand periods, e.g. during the Live Races and the San Diego Fair, the driving range is used for additional parking.

With a capacity of 44,000, it is the second largest horse-racing venue in the western United States, after the nearby Santa Anita Park.

"[27] It was built by a partnership including Bing Crosby, actors Pat O'Brien, Gary Cooper, Joe E. Brown, Charles S. Howard and Oliver Hardy.

A 100-mile AAA championship Indianapolis-type car race was held at Del Mar in November 1949, but the death of popular local driver Rex Mays in that event caused "big car" racing to disappear from Southern California circuits for 18 years.

The track hosts live racing for two seasons each year at the Del Mar Fairgrounds and can stable more than two thousand horses.

However, in February 2014 Del Mar president Joe Harper announced his intention to return to a dirt surface for the 2015 racing season.

The off-track betting facility is open during the off-season of the Del Mar Racetrack live meets.