Breeds unique to North America are printed in bold.
(F) Feral populations or breeds of feral origin.
1 Some Milking Shorthorns qualify for the "N" (Native) designation. These animals have pedigrees tracing only to ancestors registered before the herdbook was opened to outcrosses with other dairy breeds;this is a globally endangered population. The status of any Milking Shorthorn can be verified through the AMSS.
2 Includes horses registered by the Spanish Mustang Registry, Southwest Spanish Mustang Association, Spanish Barb Breeders Association, Horse of the Americas, American Indian Horse Registry, and strain registries.
3 Colonial Spanish Horse Strain that also contributes to the combined population.
4 Includes Cherokee and Huasteca influenced horses.
5 Includes Shackleford, Ocracoke, Corolla, Carrot, Core, Hatteras, and Cedar horses.
6 Includes Mt. Taylor, Baca, McKinley, but not New Mexico Horse Project horses.