Columbia Plateau | Level 3 (Parent) |
         North Columbia Plateau | Level 4 |
                 Central Washington State | Level 5 (Child) |
                 Eastern Washington Plateau | Level 5 (Child) |
                 The Palouse | Level 5 (Child) |
                 Hoodoo Mountains | Level 5 (Child) |
                 Columbia-Yakima Hills | Level 5 (Child) |
         Blue Mountains | Level 4 (Sibling) |
         Wallowa Mountains | Level 4 (Sibling) |
         Western Idaho Ranges | Level 4 (Sibling) |
         South Columbia Plateau | Level 4 (Sibling) |