What is the scientific name for the small black brown bear native to the northwestern US?

There are many subspecies of American black bears, and the NW USA has several. You need to look up the subspecies of black bears at the library to find a map, and compare that to your area of interst. There are actually no small brown bears in a black color, though there are black bears in a brown color. These bears are called cinnamon bears. Blacks also come in white, albino, blonde, glacier blue and purple (so black it has a purple hue)