Swaps field

What are there only a few hundred horses in all of CA. Every big race has 3 or 4 horses.

$350,000 Swaps Breeders' Cup Stakes (gr. II, Race 3, 1:02 p.m.), 3-Year-Olds, 1 1/8 Miles
PP. Horse, Weight, Jockey, ML Odds
1. A. P. Warrior (KY), 120, David R. Flores, 6/5
2. Potential (KY), 112, Jon K. Court, 20/1
3. Point Determined (MD), 118, Victor Espinoza, 1/1
4. Arson Squad (PA), 114, Alex O. Solis, 3/1