Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Idea Post Office (historical) | Post Office | 701 | Gilliam | 45 13 44 N | 120 03 24 W |
| Ideal Spring | Spring | 1595 | Harney | 43 48 56 N | 118 45 53 W |
| Idiot Creek | Stream | | Tillamook | 45 36 57 N | 123 25 21 W |
| Idiotville (historical) | Locale | 335 | Tillamook | 45 37 09 N | 123 25 09 W |
| Idlerest (historical) | Locale | 1282 | Klamath | 42 39 09 N | 121 53 04 W |
| Idlewild Creek | Stream | | Yamhill | 45 18 46 N | 123 22 02 W |
| Idlewild Recreation Site | Locale | 1620 | Harney | 43 47 59 N | 118 59 24 W |
| Idlewilde Cemetery | Cemetery | 160 | Hood River | 45 41 31 N | 121 31 26 W |
| Idleyld Park | Populated Place | 236 | Douglas | 43 19 25 N | 123 01 26 W |
| Idleyld Park Post Office | Post Office | 236 | Douglas | 43 19 25 N | 123 01 26 W |
| Idol City Mines | Mine | 1729 | Harney | 43 46 42 N | 118 53 39 W |
| Idol Post Office (historical) | Post Office | 1772 | Harney | 43 46 40 N | 118 54 02 W |
| Igo (historical) | Populated Place | 953 | Gilliam | 45 15 07 N | 120 16 49 W |
| Igo Butte | Summit | 895 | Gilliam | 45 16 35 N | 120 20 02 W |
| Igo Cemetery | Cemetery | 823 | Gilliam | 45 18 07 N | 120 20 02 W |
| Igo Grange Hall | Building | 955 | Gilliam | 45 15 02 N | 120 16 42 W |
| Igo Post Office (historical) | Post Office | 953 | Gilliam | 45 15 07 N | 120 16 49 W |
| Igo School (historical) | School | 857 | Gilliam | 45 16 23 N | 120 19 24 W |
| Ihrig Ranch | Locale | 1039 | Wheeler | 44 32 12 N | 120 19 40 W |
| Ike Butte | Summit | 765 | Douglas | 42 49 53 N | 123 04 28 W |
| Ike Spring | Spring | 1990 | Baker | 44 21 11 N | 118 16 04 W |
| Ikenick Creek | Stream | | Linn | 44 22 40 N | 122 00 11 W |
| Ikt Butte | Summit | 1685 | Deschutes | 43 51 26 N | 121 16 39 W |
| Ila Post Office (historical) | Post Office | 352 | Douglas | 43 36 01 N | 123 08 07 W |
| Iler Creek | Stream | | Washington | 45 35 01 N | 123 12 46 W |
| Illahe | Populated Place | 109 | Curry | 42 37 43 N | 124 03 27 W |
| Illahe Cemetery | Cemetery | 239 | Curry | 42 38 12 N | 124 04 13 W |
| Illahe Hill | Summit | 73 | Marion | 44 54 15 N | 123 06 33 W |
| Illahe Hills Country Club | Locale | 63 | Marion | 44 54 28 N | 123 06 33 W |
| Illahe Lodge | Locale | 90 | Curry | 42 38 47 N | 124 03 04 W |
| Illahe Post Office (historical) | Post Office | 109 | Curry | 42 37 43 N | 124 03 27 W |
| Illahe Recreation Site | Locale | 112 | Curry | 42 37 44 N | 124 03 29 W |
| Illahe Riffle | Rapids | 45 | Curry | 42 37 37 N | 124 03 10 W |
| Illahee Flats | Flat | 637 | Douglas | 43 17 34 N | 122 35 19 W |
| Illahee Guard Station | Locale | 667 | Douglas | 43 17 46 N | 122 34 39 W |
| Illahee Rock | Pillar | 1617 | Douglas | 43 20 57 N | 122 33 46 W |
| Illahee Spring | Spring | 1598 | Douglas | 43 21 24 N | 122 32 43 W |
| Illahee Spring | Spring | 1208 | Douglas | 43 24 39 N | 122 32 34 W |
| Illingsworth Creek | Stream | | Tillamook | 45 33 48 N | 123 53 03 W |
| Illingworth Post Office (historical) | Post Office | 77 | Tillamook | 45 29 46 N | 123 35 58 W |
| Illinois National Wild and Scenic River | Park | 296 | Curry | 42 26 14 N | 124 00 19 W |
| Illinois River | Stream | | Curry | 42 33 00 N | 124 03 58 W |
| Illinois River Forks State Park | Park | 390 | Josephine | 42 09 24 N | 123 39 29 W |
| Illinois River Trail | Trail | 1127 | Josephine | 42 26 09 N | 123 55 14 W |
| Illinois Valley Ranger Station | Building | 327 | Josephine | 42 39 37 N | 123 38 55 W |
| Illinois Valley US Forest Service Airstrip | Airport | 421 | Josephine | 42 06 15 N | 123 40 56 W |
| Illumination Rock | Pillar | 2874 | Clackamas | 45 22 04 N | 121 42 38 W |
| Ilwaco Channel | Channel | -3 | Clatsop | 46 17 40 N | 124 01 30 W |
| Image Creek | Stream | | Clackamas | 44 58 54 N | 122 21 12 W |
| Imagination Peak | Summit | 1980 | Klamath | 42 33 07 N | 122 12 08 W |
| Imbler | Populated Place | 831 | Union | 45 27 34 N | 117 57 44 W |
| Imbler Drain | Canal | 678 | Malheur | 43 43 56 N | 117 01 50 W |
| Imbler Gulch | Valley | | Wallowa | 45 35 59 N | 116 45 32 W |
| Imbler Post Office | Post Office | 831 | Union | 45 27 34 N | 117 57 44 W |
| Immigrant Gulch | Valley | | Baker | 44 45 20 N | 117 07 44 W |
| Immigrant Spring | Spring | 1001 | Wasco | 45 10 34 N | 121 28 50 W |
| Immigrant Waterhole | Reservoir | 1450 | Lake | 43 22 16 N | 120 08 31 W |
| Imnaha | Populated Place | 603 | Wallowa | 45 33 34 N | 116 49 60 W |
| Imnaha Cemetery | Cemetery | 600 | Wallowa | 45 33 20 N | 116 50 14 W |
| Imnaha Creek | Stream | | Jackson | 42 42 22 N | 122 23 20 W |
| Imnaha Divide | Ridge | 2287 | Wallowa | 45 07 56 N | 117 06 26 W |
| Imnaha Falls | Falls | 1592 | Wallowa | 45 06 26 N | 117 06 27 W |
| Imnaha Fish Weir | Dam | 1159 | Wallowa | 45 11 35 N | 116 52 10 W |
| Imnaha Grange | Locale | 867 | Wallowa | 45 22 30 N | 116 47 59 W |
| Imnaha Guard Station | Locale | 1159 | Jackson | 42 42 14 N | 122 19 55 W |
| Imnaha Post Office | Post Office | 603 | Wallowa | 45 33 34 N | 116 49 60 W |
| Imnaha Rapids | Rapids | 288 | Wallowa | 45 49 07 N | 116 45 57 W |
| Imnaha Recreation Site | Locale | 1152 | Jackson | 42 42 09 N | 122 20 04 W |
| Imnaha River | Stream | | Wallowa | 45 49 03 N | 116 45 53 W |
| Imnaha River Woods Development | Populated Place | 1267 | Wallowa | 45 15 36 N | 116 48 07 W |
| Imperial (historical) | Populated Place | 1375 | Deschutes | 43 44 49 N | 120 26 34 W |
| Imperial Eagle Mine | Mine | 2139 | Baker | 44 51 51 N | 118 16 19 W |
| Imperial Post Office (historical) | Post Office | 1376 | Deschutes | 43 44 44 N | 120 26 50 W |
| Impossible Waterhole | Reservoir | 1442 | Lake | 43 03 37 N | 120 28 19 W |
| Improved Order of Redmen Cemetery | Cemetery | 1304 | Deschutes | 43 40 29 N | 121 27 26 W |
| Inavale Post Office (historical) | Post Office | 77 | Benton | 44 27 26 N | 123 19 57 W |
| Inavale School | School | 82 | Benton | 44 27 35 N | 123 20 18 W |
| Inbetween Reservoir | Reservoir | 1560 | Malheur | 42 58 17 N | 118 08 44 W |
| Ince Camp (historical) | Locale | 795 | Wasco | 44 51 14 N | 120 33 01 W |
| Inch Creek | Stream | | Clackamas | 45 12 52 N | 121 51 12 W |
| Inch Creek | Stream | | Lane | 43 39 05 N | 122 40 45 W |
| Independence | Populated Place | 51 | Polk | 44 51 04 N | 123 11 12 W |
| Independence Bend | Bend | 43 | Marion | 44 51 39 N | 123 09 04 W |
| Independence Creek | Stream | | Baker | 44 29 59 N | 117 57 19 W |
| Independence Creek Ditch | Canal | 1193 | Baker | 44 29 15 N | 117 57 49 W |
| Independence Mine | Mine | 112 | Coos | 42 37 44 N | 124 03 29 W |
| Independence Mine | Mine | 1647 | Grant | 44 51 07 N | 118 24 25 W |
| Independence Post Office | Post Office | 51 | Polk | 44 51 04 N | 123 11 12 W |
| Independence Prairie | Flat | 83 | Marion | 44 43 19 N | 122 58 14 W |
| Independence Rock | Pillar | 869 | Linn | 44 36 44 N | 121 56 21 W |
| Independence State Airport | Airport | 54 | Polk | 44 52 04 N | 123 11 49 W |
| Independent Mine | Mine | 1748 | Crook | 44 20 29 N | 120 21 10 W |
| Independent Order of Good Templars Cemetery | Cemetery | 216 | Lane | 43 49 19 N | 123 14 16 W |
| Independent Order of Odd Fellows Cemeteries | Cemetery | 37 | Lane | 43 47 01 N | 124 05 44 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 169 | Clackamas | 45 17 49 N | 122 19 44 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 120 | Clackamas | 45 20 37 N | 122 35 05 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 13 | Columbia | 45 49 39 N | 122 50 34 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 26 | Coos | 43 11 24 N | 124 11 39 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 40 | Coos | 43 21 36 N | 124 13 14 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 161 | Douglas | 43 25 26 N | 123 18 34 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 889 | Gilliam | 45 14 38 N | 120 10 22 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 604 | Jackson | 42 11 09 N | 122 40 54 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 1251 | Klamath | 42 02 28 N | 121 38 27 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 1458 | Lake | 42 12 05 N | 120 21 03 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 94 | Linn | 44 18 19 N | 123 07 45 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 140 | Linn | 44 21 29 N | 122 52 09 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 103 | Linn | 44 33 16 N | 122 54 14 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 137 | Marion | 44 48 26 N | 122 58 26 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 736 | Sherman | 45 22 49 N | 120 47 29 W |
| Independent Order of Odd Fellows Cemetery | Cemetery | 334 | Wasco | 45 14 13 N | 121 09 46 W |