Kansas - Criteria: C (architecture/engineering)
| Norton Apartments, The |
| Oak Grove School, District 20 |
| Oak Hill Cemetery |
| Oak Lawn Farm Dairy Barn |
| Oakley High School Stadium |
| Occidental Hotel |
| Old Albany Schoolhouse |
| Old Arkansas City High School |
| Old Castle Hall, Baker University |
| Old Cawker City Library |
| Old Dutch Mill |
| Old Emporia Public Library |
| Old Frankfort City Jail |
| Old German-American State Bank |
| Oldham, James T., House |
| Old Junction City High School |
| Old Katy Bridge |
| Old Lawrence City Hall |
| Old Lawrence City Library |
| Old Mission Mausoleum |
| Old Railroad Savings and Loan Building |
| Old Santa Fe Railroad Depot |
| Old Sedgwick County Courthouse |
| Old Union Depot |
| Old Wheeler-Kelly-Hagny Building |
| Onion Creek Bridge |
| Ooten House |
| Oread Historic District |
| Orpheum Theater and Office Building |
| Osage City Santa Fe Depot |
| Osage County Courthouse |
| Osage Mission Infirmary |
| Osborne County Courthouse |
| Osborne Public Carnegie Library |
| Oswego Public Carnegie Library |
| Ott, Albert, House |
| Ottawa High School and Junior High School |
| Ottawa Library |
| Otter Creek Bridge |
| Overland Theater |
| Oxley Barn |
| Palace Theater |
| Papes Barn |
| Parachute Building |
| Paradise Water Tower |
| Parker, Martin Van Buren, House |
| Parsonian Hotel, The |
| Parsons Katy Hospital |
| Patterson House |
| Pawnee River Tributary Bridge |
| Paxico Historic District |
| Peabody City Park |
| Peabody Downtown Historic District |
| Peabody Township Carnegie Library |
| Pease, Robert L., House |
| Penley House |
| Pennsylvania Avenue Rock Creek Bridge |
| Perdue, C. A., House |
| Perring Building |
| Pettit Cleaners Building |
| Phillip Hardware Store |
| Phillipsburg Community Building |
| Pickering, I. O., House |
| Pilgrim Congregational Church |
| Pilla, Charles, House |
| Pioneer Adobe House |
| Pittsburg Public Library |
| Platt, Jeremiah, House |
| Plaza Theater |
| Pleasant Valley School District #2 |
| Plumb, Mrs. Preston B., House |
| Plymouth Congregational Church |
| Polecat Creek Bridge |
| Pottawatomie County Courthouse |
| Pottawatomie County Fair Pavilion |
| Pottawatomie Creek Bridge |
| Pott's Ford Bridge |
| Potwin Place Historic District |
| Poulet House |
| Powell House |
| Powell, Samuel, House |
| Power Plant No. 1 |
| Powers, David W., House |
| Prairie Grove School |
| Prather, Charles M., Barn |
| Pratt, John Fenton, Ranch |
| Prescott, John H., House |
| Prescott Rural High School |
| Prescott School |
| Price Villa |
| Priestly House |
| Prospect Park Farm |
| Protection High School |
| Pryor House |
| Pusch-Randell House |
| Quayle, William A., House |
| Ramsay, Ronald and Dorcas, House |
| Ransom, James H., House |
| Rapp School District No. 50 |
| Raymond, J.E., House |
Data from United States Park Service and Wikidata
