Mule deer (Odocoileus hemionus hemionus), Columbia blacktail (Odocoileus hemionus columbianus), and Sitka blacktail deer (Odocoileus hemionus sitkensis) are subspecies of the same species that are separated by geographically defined boundary (Chapter 2) lines for records-keeping purposes.
Posts
The Causes of Antler Asymmetry
PacWest Outdoors: The 9 Habits of the Record Book Buck Hunter
Boone and Crocket Scoring Sheets -A Wide World of Hunting-Deerdope
B&C WORLD RECORD TYPICAL MULE DEER
How to Score and Measure a Mule Deer - Deer Hunting
Measuring and Scoring Mule and Blacktail Deer - B&C Club Official Guide
blacktail buck
BC Mule Deer, as it Happens.
Big Game Records - New Mexico Department of Game & Fish
Sitka (Blacktail) Deer Shoulder Mount For Sale #18092 - The Taxidermy Store
Entry Requirements, Pope and Young Club
First buck, how do I score him? : r/Hunting