American Black Bear Subspecies

Sub-Species Name	Common Name	Distribution	Description
Ursus americanus altifrontalis		Found in the Pacific Northwest coast from central British Columbia through northern California and inland to the tip of northern Idaho and British Columbia
Ursus americanus amblyceps		Native to Colorado, New Mexico, west Texas, the eastern half of Arizona into northern Mexico; southeastern Utah
Ursus americanus americanus		Found in eastern Montana to the Atlantic coast; from Alaska south and east through Canada to the Atlantic and south to Texas. Thought to be increasing in some regions.
Ursus americanus californiensis		Found in the mountain ranges of Southern California, north through the Central Valley to southern Oregon
Ursus americanus carlottae	Haida Gwaii Black Bear	Haida Gwaii/Queen Charlotte Islands and Alaska	Generally larger than its mainland counterparts with a huge skull and molars, and is only found as a black color phase
Ursus americanus cinnamomum	Cinnamon Bear	Idaho, western Montana, and Wyoming, eastern Washington and Oregon, northeastern Utah	Has brown or red-brown fur, reminiscent of cinnamon.
Ursus americanus emmonsii		southeastern Alaska. Stable.	Distinguished by the fur of its flanks being silvery gray with a blue lustre
Ursus americanus eremicus		northeastern Mexico. Endangered.
Ursus americanus floridanus	Florida Black Bear	Florida, southern Georgia, and Alabama. Threatened in Florida as the Florida Black Bear (state list).	Has a light brown nose, and shiny black fur. A white chest patch is also common. An average male weighs 299 pounds (136 kg)
Ursus americanus hamiltoni	Newfoundland Black Bear	Newfoundland	Generally bigger than its mainland relatives, ranging in size from 90 to 270 kg and averaging 135 kg. It also has one of the longest hibernation periods of any bear in North America
Ursus americanus kermodei	Kermode Bear, Spirit Bear	Central coast of British Columbia	Has white fur due to a rare genetic trait
Ursus americanus luteolus	Louisiana Black Bear	Eastern Texas, Louisiana, southern Mississippi. Threatened (federal list).	A subspecies with a relatively long, narrow, and flat skull, and proportionately large molar teeth
Ursus americanus machetes		North-central Mexico
Ursus americanus perniger		Kenai Peninsula, Alaska
Ursus americanus pugnax		Alexander Archipelago, Alaska
Ursus americanus vancouveri		Vancouver Island, British Columbia

Taxonomy and evolution

Although they all live in North America, American black bears, brown bears, and polar bears are not closely related, genetic studies have revealed that they split from a common ancestor before about 5,05 million years. Both American and Asiatic black bears are considered sister taxa, and are more related to each other than other bears species.

A small primitive bear called Ursus abstrusus is the oldest known North American fossil member of the genus Ursus, dated to 4.95 millions years ago. This suggests that U. abstrusus may be the direct ancestor of the American black bear, which evolved in North America. Although Wolverton and Lyman still consider U. vitabilis an "apparent precursor to modern black bears", it has also placed within U. americanus.

Ancestor of the American black bear and the Asian black bear diverged from sun bears 4.58 million years ago. Then the American black bear separated from the Asian before about 4.08 million years ago. The earliest fossils of American black bears, which are located in Port Kennedy, Pennsylvania, greatly resemble the Asiatic species, though later specimens grew to sizes comparable to grizzlies. From the Holocene to present, American black bears seem to have shrunk in size, but this was rejected due to issues of aging of the fossil samples.

American black bear lived in the same period as as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 7–8 millions years ago. The short-faced bears are thought to have been heavily carnivorous and the FL spectacled bear more herbivorous, while the American black bears remained arboreal omnivores, like their Asian ancestors. The black bear's generalist behavior allowed it to exploit a wider variety of foods and has been given as a reason why of these 3 genera, is the only survived climatic and vegetative changes during and after the Ice Age, while others more specialized North American predators extinct. However, both Arctodus and Tremarctos had survived several other ice ages. After these prehistoric Ursids went extinct during the last glacial period 10,000 years ago, black bears are probably the only bears in much of North America, while brown bears did not come into the rest of continent.