The American Bulldog descended from the original working English Bulldogs that descended from ancient Mastiffs. Bulldogs in old England hunted large prey such as bears and lions. English butchers and farmers used them to catch cattle and boars using their 'lock jaw' grip to hang on until the very end.

These original English Bulldogs resemble the leggier American Bulldog of today than the more shorter, stockier dog we know as the British Bulldog. In 1835, the blood sport of "baiting" was declared illegal so the number of purebred Bulldogs in England declined. Purebred Bulldogs were shipped to the United States which increased in numbers and was used to protect property and catch free-range hogs and stray cattle in the South and South West of the country. The Bulldogs that were left in old England developed into the show dog we know today as the British Bulldog.

Bulldogs in the United States became almost extinct by the late 1960s so a handful of dedicated breeders kept the Bulldog thriving. Allen Scott, John D. Johnson, Jack Tate, W.C. Bailey, Rayburn Stover, Cell Ashley, and Louie Hegwood are all foundation breeders of the modern American Bulldog. These breeders shared a common goal but their perfect ideal American Bulldog differed.

The two main strains as a result are the Johnson (Bully type) which are larger with broader head, wider dog with more bone, pendulous lips, an undershot jaw, facial wrinkles and a shorter muzzle. The Scott (Standard type) have a longer muzzle, are leggier and not as massive as the Bully type.

The Bully type descended from plantation guard dogs of the South, are generally more territorial and aggressive while the Standard type are more athletic and comes from the lines of hog and cattle dogs.