Bull and terrier breeds were created in early 19th-century England for the popular spectator sports of bull- and bear-baiting. When those sports were deemed inhumane and became illegal 1835, dog-fighting sprung up in its place — and thus was the trait for dog aggression bred into the genetic line.
But another part of this breed’s genetic makeup is an unwillingness to bite humans. Handlers reaching into the dog-fighting rings wanted to be able to separate dogs without getting hurt themselves. Quite soon the breed developed a reputation as a strong, protective dog, but one also known for being gentle and family-friendly.
When these “bull dogs” accompanied immigrants to America they began new careers as all-around farm dogs. Their jobs included hunting wild game, guarding the property from animal intruders, and providing companionship. In keeping with the “bigger is better” mindset of their new country, the settlers developed a dog larger than it had been in England.
In 1898 the UKC, Britain’s equivalent of the AKC, named these bull dogs the American Pit Bull Terrier. The AKC decided to recognize the breed in the early 1930s — but under a new name. Intending to separate it from its pit-fighting past, the AKC named it the American Staffordshire Terrier.
Since then the American Staffordshire Terrier has been bred for AKC conformation, or dog shows, while the American Pit Bull Terrier has not been. The results are very slight differences in build and in personality.