The History and Origin of the American Bulldog
Regarding the American Bulldog's origins there are three main theories.
According to the first one, the American Bulldog was brought over to America by the colonists, where they were primarily used as farm guards, stock dogs gathering cattle and as pack dogs to hunt or tree bears. It is, according to this theory, the "original" English Bulldog which has survived unchanged in remote rural communities, just as it was when it was still a working breed rather than the present-day English Bulldog.
According to the second one, the American Bulldog is a "made-up" breed concocted from a mixture of other breeds in the last 50 years.
The third one consists of a combination of theories (1) and (2). Basically, the "original" English Bulldog was an ancestor of today's American Bulldog but he has been much modified through the years by selective breeding and judicious outcrosses. We should remember at this point that many of the bullbreeds we know today are ultimately descended from the "original" English Bulldog: this includes Bullmastiffs, Staffordshires, English Bull Terriers and American Pit Bull Terriers among others. All of these were selectively bred to create very different dogs, each suited to his individual purpose.
The advocates of the first theory believe the American Bulldog is the pure embodiment of the original English Bulldog as it looked when the early settlers from the British Isles and Europe came to America in the 17th and 18th centuries. This idea was popularized by a couple of breeders, probably as a marketing ploy to sell their dogs. Others have eagerly swallowed the story, enabling its passage from myth to modern legend to widely-perceived truth.
Records do exist which show that many bulldogs and bull terriers were exported to America and many contemporary British paintings and sculptures show bulldogs which look similar to American Bulldogs, and many people point to these as evidence to support this belief.
The white coloring predominant in today's American Bulldogs was also the base color of most of the English bulldogs of that times, which could suggest a very strong link. However, it seems highly unlikely that the original English bulldog could possibly have survived unchanged in America for hundreds of years; through the generations he would have been interbred and shaped by his environment and the needs of his masters. This theory does have a certain romantic attraction to it however, so it is easy to understand it's continuing popularity.
The advocates of the second theory believe the American Bulldog was created from a blend of various types of dog, which of course is true for every breed. More important is to know what exactly where the foundation dogs of these breeding programs, hence, the third theory option.
The third theory, and the probably the one closest to the truth, is that the American Bulldog is descended from a selectively-bred blend of bulldogs and bull terriers. Immigrants from the British Isles, Spain and Northern Europe brought their prized bulldogs and bull terriers with them on their voyage to the New World, where they would certainly have proved their worth in many ways. The dogs provided welcome protection in a sometimes hostile land and also were invaluable to the livestock farmer whose cattle and pigs roamed unfenced over wide areas; this made the livestock hard for the farmer to catch when required, and so the "catch dog" came into being. The selective breeding that had created a dog with the strength, tenacity, courage and longing to seize a bull at a baiting or engage in some other form of animal combat now made him the free-range livestock farmer's best friend. In his new role the bulldog could seize a cow or pig and and hold him firm until his handlers joined him to tie or slaughter the animal. In addition those same abilities made him a most formidable tool for hunting wild game, a scenario the American Bulldog continues to excel in today in parts of the United States. His major role however was as a general watchdog and companion more than anything else, which continues to be the breed's forte.
Pedigrees or other records were not kept, these were not show dogs so there was no need. Natural selection governed the development of the bulldog in America in those times, and as working dogs in a harsh world, poor performing dogs either died in action or would be culled by their owners. Breedings would be decided purely on a dog's abilities: If you had a good bitch and wanted a litter and you knew someone who had a good proven dog then a tie might be arranged to create another generation of working bulldogs, some of which may have been sold to provide a little extra cash in those tough times.
Many breeding experiments would undoubtedly have been tried over the many decades that have elapsed since those first bulldogs and bull terriers landed in America, some successful and some probably less so. For example, some hound blood was likely crossed in to help enhance the breed's hunting/tracking/baying abilities. Higher proportions of terrier blood would have added tenacity and quickness to some strains too. An extra dose of modern "sour-mug" English Bulldog blood has apparently been added by at least one well known breeder in fairly recent history to increase the "bulliness" of his lines. A couple of mystery ingredients have probably been added too at some points back in the past. This old recipe probably holds true for all lines/types of American Bulldog with only the proportions of ingredients varying. However the American bulldog is now certainly far enough away from its "root-breeds" to unquestionably be regarded a true breed in its own right, and a fine and versatile one too.