The answer lies in genetics and pigmentation.
Rabbit coat colors are influenced by inherited variations affecting the production, distribution, and expression of pigment.
The two major forms of melanin involved in mammalian pigmentation are eumelanin, associated with black and brown coloration, and pheomelanin, associated with reddish and yellowish tones.
In blue rabbits, the appearance usually results from a genetic dilution of black pigmentation.
Instead of producing the visual effect of a dense black coat, inherited pigment-distribution characteristics make the fur appear blue-gray.
In simplified rabbit color genetics, the dilution locus is commonly represented by the letter D.
The recessive combination dd produces diluted pigmentation, which can turn a genetically black coat into a blue appearance.
However, this is only part of a larger genetic system.
Other genes affect the underlying coat color, pattern, and expression of pigments.
A specialist article published by the Breeders of the American Rabbit National Specialty Club explains how several major genetic loci interact to determine coat colors in American rabbits.
The article also illustrates why breeding blue and white rabbits can produce unexpected color combinations when the animals carry different hidden genetic variants.
This genetic complexity helps explain why developing a consistent breed can require careful selection across many generations.
A breeder cannot simply mate any two blue rabbits and expect their descendants to match a precise breed standard.
Body shape, size, coat quality, pigmentation, and other traits must be considered together.
Salisbury's accomplishment therefore involved more than producing an attractive color.
The American Blue became a recognizable breed because its defining characteristics could be reproduced and maintained through selective breeding.
Exactly how Salisbury achieved that result remains uncertain.
Modern genetic analysis might help researchers understand relationships among surviving rabbit populations, but genetics would not automatically reconstruct every cross made more than a century ago.
The original breeding animals may no longer exist, and generations of subsequent selection can obscure historical relationships.
Without authenticated genetic material from the founders and suitable comparison populations, the precise ancestral combination may remain impossible to establish with certainty.
The mystery is therefore not necessarily hidden in one easily identifiable genetic marker.
It concerns an entire breeding history.
Why the Breed's Name Changed
Another fascinating aspect of the American Blue's history is that it was not always known by its modern name.
According to The Livestock Conservancy, the breed was initially known as the German Blue Vienna.
That name reflected an association with European blue rabbit breeding.
However, its development took place during a politically and socially turbulent period.
The United States entered World War I in April 1917.
Anti-German sentiment became widespread during the conflict, influencing aspects of American public life, including the names used for certain products and organizations.
The rabbit breed's name changed during this historical atmosphere.
The Livestock Conservancy explains that German Blue Vienna was replaced with American Blue in connection with World War I.
The new name emphasized the breed's American development and separated its identity from the older European terminology.
It also became a lasting part of the breed's heritage.
Although some of its proposed ancestors may have originated in Europe, the American Blue emerged as a distinct breed through the work of breeders in the United States.
This transformation illustrates how the history of domestic animals can intersect with broader human events.
Breed names are not always based exclusively on genetics or geography.
They can also reflect the cultural circumstances in which animals become established and recognized.
From an Unusual Rabbit to a Valuable Agricultural Animal
The American Blue did not remain merely a curiosity displayed at rabbit exhibitions.
Following its introduction, it became increasingly valued for practical agricultural purposes.
During the early twentieth century, rabbit breeding could provide households and farmers with useful products and additional income.
The American rabbit was developed as a dual-purpose breed, valued particularly for meat and fur.
Its large body and long loin contributed to meat production, while the distinctive coloring of its coat made its fur attractive to buyers.
The Livestock Conservancy reports that, around 1920, a desirable rabbit pelt could command approximately two dollars, while a breeding-age doe could start at twenty-five dollars.
These were meaningful sums during that period.
The breed's commercial appeal helped it spread beyond California.
Its reputation was supported by its productive qualities, including its generally docile behavior and suitability for breeding.
Historical accounts describe American does as capable mothers, another characteristic valued by farmers maintaining breeding populations.
Over time, the American rabbit became a familiar presence within the country's rabbit-breeding community.
A historical American Rabbit Breeders Association guidebook from the 1920s praised its combination of useful size, development, and fur-producing qualities.
That record demonstrates that the breed's appeal was not limited to appearance alone.
The American Blue was associated with a practical agricultural system in which carefully selected animals contributed to household livelihoods and small-scale farming operations.
Its success reflected the priorities of an era when versatility was especially valuable.
The Arrival of the American White
Although the American Blue was the original variety, its history eventually expanded to include another distinctive rabbit.
In 1925, the American White was officially recognized.
This variety developed from white offspring appearing within American Blue breeding lines, together with the introduction of White Flemish Giant ancestry.
The American White has a pure white coat and pink or reddish-looking eyes, characteristics associated with albinism.
Despite the dramatic difference in appearance, the American Blue and American White belong to the same established breed.
This development also illustrates the complexity of inherited traits.
A white rabbit can carry genetic variants affecting pigmentation that remain visually hidden because albinism prevents the normal expression of coat color.
Consequently, breeding blue and white American rabbits does not always produce the straightforward results an inexperienced observer might expect.