- Lake
(17 historic properties)
- Lane
(134 historic properties)
- Lincoln
(34 historic properties)
- Linn
(66 historic properties)
- Malheur
(17 historic properties)
- Marion
(109 historic properties)
- Morrow
(4 historic properties)
- Multnomah
(561 historic properties)
- Polk
(26 historic properties)
- Sherman
(5 historic properties)
- Tillamook
(29 historic properties)
- Umatilla
(40 historic properties)
- Union
(19 historic properties)
- Wallowa
(15 historic properties)
- Wasco
(31 historic properties)
- Washington
(43 historic properties)
- Wheeler
(1 historic property)
- Yamhill
(79 historic properties)