The American pit bull terrier is the product of interbreeding between terriers and a breed of bulldogs to produce a dog that combined the gameness of the terrier with the strength and athleticism of the bulldog.^[9]These dogs were initially bred in England, Ireland, and Scotland, and arrived in the United States with immigrants from these countries. In the United States, these dogs were used as catch dogs for semi-wild cattle and hogs, to hunt, to drive livestock, and as family companions;^[9] however, some were selectively bred for their fighting prowess.^[10] [11]

The United Kennel Club (UKC) was the first registry to recognize the American pit bull terrier.^[12] UKC founder C. Z. Bennett assigned UKC registration number 1 to his own dog, "Bennett's Ring", as an American pit bull terrier in 1898.^[9]

American pit bull terriers today successfully fill the role of companion dog, police dog,^[13][14] and therapy dog;^[15] however, terriers in general have a higher tendency towards dog aggression^[16] and American pit bull terriers constitute the majority of dogs used for illegal dog fighting in the United States.^[17] In addition, law enforcement organizations report these dogs are used for other nefarious purposes, such as guarding illegal narcotics operations,^[18] use against the police,^[19] and as weapons.^[20]

The fighting reputation of pit bull-type dogs led the San Francisco Society for the Prevention of Cruelty to Animals in 1996 to relabel pit bull terriers as "St. Francis terriers" (not associated with the "terrier" mascot of St. Francis College in New York) so that they might be more readily adopted;^[21] 60 temperament-screened dogs were adopted until the program was halted after several of the newly adopted dogs killed cats.^[22] The New York City Center for Animal Care and Control tried a similar approach in 2004 by relabeling their pit bull terriers as "New Yorkies", but dropped the idea in the face of overwhelming public opposition.^[23][24]