The Blacktail or Black-tailed deer is a species of the deer found in western North America,
They once lived at least as far east as Wyoming.
The Black-tailed deer is currently common in northern California, western Oregon, Washington, in coastal and interior British Columbia, and north into the Alaskan panhandle.
It was once believed to be a subspecies of the North American mule deer (Odocoileus hemionus), however, recent DNA testing has proven this not to be the case.
Reference: http://www.thehunterwiki.com/?title=Blacktail_Deer