Oregon - Area of significance: Architecture
| Monroe State Bank Building |
| Monteith Historic District |
| Monteith,Thomas and Walter,House |
| Montgomery Ward & Company |
| Moody, Malcolm A., House |
| Mooers, Dr. Robert R. and Mary Helen, House |
| Moore, John and Helen, House |
| Moore, John and Mary, House |
| Moore, Robert D., House |
| Morgan Building |
| Morgan, Melinda E., House |
| Morrow County Courthouse |
| Morse House |
| Morse House |
| Morse, Wayne, Farm |
| Moser, Joseph Henry, Barn |
| Mosier, Jefferson, House |
| Mountain House |
| Mount Hood Masonic Temple |
| Mount Tabor Park Reservoirs Historic District |
| Moyer, John M., House |
| Mt. Hood School House |
| Mt. Pleasant Presbyterian Church |
| Mt. Stella Lookout |
| Multnomah County Courthouse |
| Multnomah Falls Lodge and Footpath |
| Multnomah Hotel |
| Multnomah School |
| Munsell, William O., House |
| Munson Valley Historic District |
| Murphy, Lester and Hazel, House |
| Murphy, Paul C., House |
| Murphy, Paul F., House |
| Musick Guard Station |
| Myrtle Arms Apartment Building |
| Nasburg-Lockhart House |
| Nauke, William and Nannie, House |
| Neighborhood House |
| Neighbors of Woodcraft Building |
| Nelson, Carl E., House |
| Nelson, Otto W. and Ida L., House |
| Neuberger, Isaac, House |
| Nevada-California-Oregon Railway Passenger Station |
| New Cliff House |
| Newell, Edwin, House |
| New Fliedner Building |
| New Heathman Hotel |
| New Houston Hotel |
| New Logus Block |
| Newman United Methodist Church |
| New Redmond Hotel |
| New Taggart Hotel |
| Nicholas-Lang House |
| Nichols, Dr. A. S., House |
| Nichols, Dr. Herbert S., House |
| Nicolai-Cake-Olson House |
| Nicolai, Harry T., House |
| Nininger, Amos and Vera, House |
| Noonan-Norblad House |
| North Palestine Baptist Church |
| Northwestern Electric Company-Alberta Substation |
| Northwestern National Bank Building |
| Oak Grove Schoolhouse |
| Oakland Historic District |
| Odd Fellows Building |
| Odem, Milton, House |
| O'Donnell, E. J., House |
| O'Kane Building |
| Olallie Lake Guard Station |
| Olallie Meadows Guard Station |
| Old First National Bank Building |
| Old First National Bank of Prineville, and Foster and Hyde Store |
| Old Garfield School |
| Old Scotch Church |
| Olds, Wortman and King Department Store |
| Old Town Historic District |
| Old US Post Office |
| Old Woodburn City Hall |
| Old Yaquina Bay Lighthouse |
| Oleson, Ole and Polly, Farmhouse |
| Olsen and Weygandt Building |
| Olson, August, House |
| Olson, Charles and Fae, House |
| Olympic Apartment Building |
| Olympic Cereal Mill |
| Oregon Bank Building |
| Oregon Caves Chateau |
| Oregon Caves Historic District |
| Oregon City Carnegie Library |
| Oregon City Masonic Lodge |
| Oregon City Municipal Elevator |
| Oregon Cracker Company Building |
| Oregon Electric Railway Passenger Station |
| Oregon Mutual Merchant Fire Insurance Association Office |
| Oregon Portland Cement Building |
| Oregon Power Company's Springfield Substation |
| Oregon Short Line Railroad Depot |
| Oregon State Capitol |
| Oregon State Fair Stadium and Poultry Building Ensemble |
| Oregon State Forester's Office Building |
Data from United States Park Service and Wikidata
