| Oberly | John | 113 | |
| Oberly | Kathryn | M. | 113 |
| Ochampaugh | Leona | June | 52 |
| Ochanpaugh | Leona | J. | 52 |
| O'Daniel | Anna | B. | 122 |
| O'Day | Mary | 20 | |
| O'Day | Patrick | 116 | |
| O'Keefe | Melody | 149 | |
| Oles | Maude | Saxton | 69 |
| Olmstead | John | 15 | |
| Olmstead | Mary | Elisabeth | 15 |
| Ols-Datter | Astrid | 1 | |
| Olsen | Edward | Andrew | 62 |
| Olsen | Rosetta | May | 62 |
| Olson | LaDonna | Mae | 1 |
| O'Mara | Anna | J. | 66 |
| O'Mara | Eugene | E. | 66 |
| O'Mara | Frank | R. | 66 |
| O'Mara | Frank | Roman | 66 |
| O'Mara | John | 66 | |
| O'Mara | Lawrence | J. | 66 |
| O'Mara | Marie | J. | 66 |
| O'Mara | Mary | C. | 66 |
| O'Mara | Norma Louise | Shoemaker McCaul | 166 |
| O'Mara | Pauline (Peggy) | A. | 66 |
| O'Mara | Rosemary | F. | 66 |
| O'Mara | Thomas | P. | 66 |
| O'Mara | Thomas | S. | 66 |
| O'Mara | Winifred | 66 | |
| Onion | Edna | Olive | 88 |
| Onion | Jasper | Newton | 88 |
| Opthoff | Donna | 130 | |
| Opthoff | John | Douglas | 130 |
| Opthoff | John | Martin | 130 |
| Orr | Harry | 20 | |
| Orr | Isabella | 1 | |
| Orr | Marjorie | 20 | |
| Osbore? | Lucinda | 1 | |
| Osborn | Harriet | Ann | 37 |
| Osborn | Harriet | Ann | 135 |
| Osborn | Harriet | Ann | 153 |
| Osborn | Maria | B. | 1 |
| Osgood | Almira | 157 | |
| Osgood | Basheba | Brown | 157 |
| Osgood | Carra | 1 | |
| Osgood | Dorr | 157 | |
| Osgood | Edith | 1 | |
| Osgood | Emeline | 1 | |
| Osgood | Emma | 1 | |
| Osgood | Gladys | 1 | |
| Osgood | Harry | 157 | |
| Osgood | Leonard | Mrs. | 76 |
| Osgood | Ruma | Hull | 76 |
| Osgood | Sarah | Sabin | 157 |
| Oswald | Jessie | 39 | |
| Oswald | Robert | 39 | |
| Otis | Omon | 130 | |
| Otrambo | Cathryn | M. | 124 |
| Otrambo | Cathryn | M. | 145 |
| Otrambo | Maxine | Jean Smith | 145 |
| Otrambo | Robert | Neil | 124 |
| Otrambo | Robert | Neil | 145 |
| Otte | Mae | 66 | |
| Otterbein | Conrad | 115 | |
| Otterbein | Louise | 115 | |
| Otto | Albert | F. | 51 |
| Outman | Carolyn | Face | 15 |
| Outman | Robert | Gerald | 15 |
| Overhiser | George | C | 40 |
| Owen | John | 89 | |
| Owen | Martha | 89 | |
| Owen | Obidiah | 89 | |
| Owrey | Caroline | Grinnell | 14 |
| Owrey | Jacob | 14 | |
| Owrey | Samantha | Grinnell | 14 |