they break the BT into 2 Columbian and Cascade I believe. As far as breaking them you can get crosses in MD and blacktail. I know when I took my BT into score it was from Stevens Pass down to start of Snohomish County for Cascade BT
The State book for Oregon and Washington is the only organization that splits the blacktail into two species Columbia and Cascade.
Pope and Young only recongnizes one species of the Columbia Blacktail Deer. Here is the Boundary for Washington State Columbia Blacktail Deer.
Beginning at the Washington-British Columbia border, the boundary line runs south along the west boundary of North Cascades National Park to the range line between R10E and R11E, Willamette Meridian, which is then followed directly south to its intersection with the township line between T18N and T17N, which is then followed westward until it connects with the north border of Mt. Rainier National Park, then along the north, west and south park boundaries until it intersects with the range line between R9E and R10E, Willamette Meridian, which is then followed directly south to the Columbia River near Cook
