Oregon - Significance region: Local
| Imperial Stock Ranch Headquarters Complex |
| Independence Historic District |
| Independence National Bank |
| Independent School |
| Indian Shaker Church and Gulick Homestead |
| Inman, Clarissa McKeyes, House |
| International Harvester Company Warehouse |
| IOOF Building |
| IOOF-Paris Fair Building |
| Ireland, Sarah E., House |
| Iron Workers' Cottage |
| Irving Street Bowman Apartments |
| Irvington Bowman Apartments |
| Irvington Historic District |
| Irwin, Richard S., Barn |
| Italian Gardeners and Ranchers Association Market Building |
| Jackson County Courthouse |
| Jacksonville-to-Fort Klamath Military Wagon Road |
| Jacobberger, Josef, House |
| Jacobs-Wilson House |
| James, W. Leland, House |
| Jantzen, Carl C., Estate |
| Jantzen Knitting Mills Company Building |
| Jarman, Daniel B., House and Garden |
| J.C. Penney Building |
| Jeanne Manor Apartment Building |
| Jefferson County Courthouse |
| Jefferson Methodist Church |
| Jefferson Substation |
| Jeffrey, Oliver and Margaret, House |
| Jenkins, Belle Ainsworth, Estate |
| Jensen Investment Company Building |
| Jeppesen, Peter, House |
| Jessen-Goodrich House |
| Jewish Shelter Home |
| J.L. Elam Bank |
| Johnson, C. D., House |
| Johnson, Charles E., Building |
| Johnson-Ellis House |
| Johnson Hall |
| Johnston, Andrew J. and Anna B., Farmstead |
| Jones Cash Store |
| Jones, Clarence H., House |
| Jones, Dr. Noble Wiley, House |
| Jones-Sherman House |
| Jones, Simpson E., House |
| Jorgensen, Victor H. and Marta, House |
| Journal Building |
| Julian Hotel |
| Kane, E. C., House |
| Keating, John A. and Hattie Mae, House |
| Keck, H.C., House-Mt. Olivet Parsonage |
| Keller, Edward H. and Bertha R., House |
| Kelty, James M. and Paul R., House |
| Kendall, Joseph, House |
| Kennedy, John D., Elementary School |
| Kenton Commercial Historic District |
| Kenton Hotel |
| Kern, Grace, House |
| Kerr, Albertina, Nursery |
| Kershaw, Dr. Andrew, House |
| Kienlen-Harbeck Building |
| Kiernan House |
| King, Charles, House |
| King, Isaac, House and Barn |
| King, Samuel W., House |
| King's Hill Historic District |
| Kingsley, Edward D., House |
| Kinsman, John and Elizabeth, House |
| Kirk, John W., and Thomas F., House |
| Kirkland Lookout Ground House (Guard Station) |
| Kistner, Dr. Frank B., House |
| Klamath County Armory & Auditorium |
| Klamath Falls City Hall |
| Klamath Falls City Library, Old |
| Kline, Lewis G., Building |
| Kline, Lewis G., House |
| Kline, Moses, and Ida, House |
| Knight, F. M., Building |
| Knight, William, House |
| Kohlhagen Building |
| Koontz, James H. and Cynthia, House |
| Koontz, J.H., Building |
| Koski Building |
| Kraft-Brandes-Culberston Farmstead |
| Kress Building |
| Krietz House |
| Krouse, Nettie, Fourplex |
| Kuehle, Henry, Investment Property |
| Kyle, William, and Sons, Building |
| Ladd Carriage House |
| Ladd Estate Company Model House |
| Ladd's Addition Historic District |
| LaDow Block |
| La Grande Commercial Historic District |
| La Grande Neighborhood Club |
| Lake County Round Sale Barn |
| Lake Oswego Hunt Club Ensemble |
| Lake Oswego Odd Fellows Hall |
| Lamport, Frederick S., House |
Data from United States Park Service and Wikidata
