| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| O'Fallon | city | Missouri | United States | 38.67 | -90.23 | 830 | |
| O'Fallon | city | Missouri | United States | 38.81 | -90.70 | 830 | |
| Oak | city | Missouri | United States | 39.89 | -94.53 | 967 | |
| Oak Grove | city | Missouri | United States | 39.01 | -94.13 | 872 | |
| Oak Grove | city | Missouri | United States | 37.57 | -90.39 | 830 | |
| Oak Grove Heights | city | Missouri | United States | 37.17 | -93.12 | 1669 | |
| Oak Grove Village | city | Missouri | United States | 38.23 | -91.15 | 902 | |
| Oak Hill | city | Missouri | United States | 38.21 | -91.42 | 885 | |
| Oak Mound | city | Missouri | United States | 36.68 | -92.18 | 898 | |
| Oak Ridge | city | Missouri | United States | 36.71 | -93.79 | 1669 | |
| Oak Ridge | city | Missouri | United States | 36.03 | -89.84 | 252 | |
| Oak Ridge | city | Missouri | United States | 37.50 | -89.73 | 830 | |
| Oak Ridge | city | Missouri | United States | 37.86 | -94.15 | 830 | |
| Oakdale | city | Missouri | United States | 39.76 | -91.93 | 830 | |
| Oakdale (historical) | city | Missouri | United States | 37.34 | -91.07 | 1164 | |
| Oakhill | city | Missouri | United States | 36.50 | -93.71 | 1099 | |
| Oakland | city | Missouri | United States | 37.64 | -92.56 | 1197 | |
| Oakland | city | Missouri | United States | 38.58 | -90.39 | 830 | |
| Oakland (historical) | city | Missouri | United States | 38.97 | -93.84 | 830 | |
| Oakland Park | city | Missouri | United States | 37.11 | -94.48 | 997 | |
| Oakley | city | Missouri | United States | 37.15 | -90.96 | 830 | |
| Oakmont | city | Missouri | United States | 36.53 | -93.28 | 997 | |
| Oaks | city | Missouri | United States | 39.20 | -94.57 | 951 | |
| Oakside | city | Missouri | United States | 37.11 | -91.65 | 1200 | |
| Oakton | city | Missouri | United States | 37.46 | -94.35 | 935 | |
| Oakvale | city | Missouri | United States | 38.09 | -90.46 | 830 | |
| Oakview | city | Missouri | United States | 39.21 | -94.57 | 984 | |
| Oakville | city | Missouri | United States | 38.47 | -90.30 | 830 | |
| Oakville | city | Missouri | United States | 36.15 | -89.90 | 252 | |
| Oakwood | city | Missouri | United States | 39.20 | -94.57 | 951 | |
| Oakwood | city | Missouri | United States | 39.69 | -91.40 | 830 | |
| Oakwood Manor | city | Missouri | United States | 39.20 | -94.56 | 951 | |
| Oakwood Park | city | Missouri | United States | 39.20 | -94.57 | 1000 | |
| Oasis | city | Missouri | United States | 39.08 | -90.75 | 830 | |
| Oasis (historical) | city | Missouri | United States | 36.54 | -93.30 | 912 | |
| Oasis Mobile Home Park | city | Missouri | United States | 38.80 | -94.53 | 997 | |
| Oates | city | Missouri | United States | 37.56 | -91.06 | 1020 | |
| Ocie | city | Missouri | United States | 36.56 | -92.76 | 830 | |
| Octa | city | Missouri | United States | 36.17 | -90.12 | 259 | |
| Odessa | city | Missouri | United States | 39.00 | -93.95 | 898 | |
| Odin | city | Missouri | United States | 37.27 | -92.62 | 1669 | |
| Oermann | city | Missouri | United States | 38.31 | -90.72 | 830 | |
| Oetters | city | Missouri | United States | 38.56 | -90.79 | 830 | |
| Ogborn | city | Missouri | United States | 37.83 | -90.42 | 944 | |
| Ogden | city | Missouri | United States | 36.74 | -89.56 | 308 | |
| Oglesville | city | Missouri | United States | 36.58 | -90.31 | 308 | |
| Ohio | city | Missouri | United States | 38.16 | -93.85 | 869 | |
| Ohlman | city | Missouri | United States | 37.43 | -91.12 | 1200 | |
| Oil City | city | Missouri | United States | 39.34 | -92.85 | 830 | |
| Okete | city | Missouri | United States | 39.10 | -90.93 | 830 | |
| Olathia | city | Missouri | United States | 37.03 | -92.52 | 1108 | |
| Old Appleton | city | Missouri | United States | 37.60 | -89.71 | 830 | |
| Old Bland | city | Missouri | United States | 38.32 | -91.62 | 846 | |
| Old Chilhowee | city | Missouri | United States | 38.61 | -93.85 | 830 | |
| Old Greenville (historical) | city | Missouri | United States | 37.10 | -90.45 | 400 | |
| Old Linn Creek | city | Missouri | United States | 38.07 | -92.74 | 830 | |
| Old Merritt | city | Missouri | United States | 36.90 | -92.89 | 1145 | |
| Old Mines | city | Missouri | United States | 38.02 | -90.76 | 830 | |
| Old Monroe | city | Missouri | United States | 38.93 | -90.75 | 830 | |
| Old North Saint Louis | city | Missouri | United States | 38.65 | -90.20 | 830 | |
| Old Pattonsburg | city | Missouri | United States | 40.05 | -94.14 | 830 | |
| Old Peculiar | city | Missouri | United States | 38.72 | -94.44 | 980 | |
| Old Shawnee Village (historical) | city | Missouri | United States | 36.94 | -89.89 | 396 | |
| Old Success | city | Missouri | United States | 37.46 | -92.09 | 1669 | |
| Old Town | city | Missouri | United States | 36.50 | -91.54 | 830 | |
| Old Westport Landing | city | Missouri | United States | 39.18 | -90.73 | 830 | |
| Old Woollam | city | Missouri | United States | 38.39 | -91.55 | 830 | |
| Olden | city | Missouri | United States | 36.83 | -91.91 | 1207 | |
| Oldfield | city | Missouri | United States | 36.98 | -93.04 | 1669 | |
| Oldham | city | Missouri | United States | 38.73 | -92.26 | 905 | |
| Olean | city | Missouri | United States | 38.41 | -92.53 | 830 | |
| Olga | city | Missouri | United States | 37.09 | -92.91 | 1669 | |
| Olinger | city | Missouri | United States | 37.28 | -93.84 | 1154 | |
| Olive | city | Missouri | United States | 37.46 | -93.11 | 1669 | |
| Olivette | city | Missouri | United States | 38.67 | -90.38 | 830 | |
| Olney | city | Missouri | United States | 39.08 | -91.24 | 830 | |
| Olson Acres | city | Missouri | United States | 38.78 | -94.52 | 997 | |
| Olympia | city | Missouri | United States | 37.73 | -94.03 | 898 | |
| Olympian Village | city | Missouri | United States | 38.14 | -90.46 | 830 | |
| Omaha | city | Missouri | United States | 40.53 | -92.80 | 954 | |
| Omba (historical) | city | Missouri | United States | 36.87 | -92.16 | 935 | |
| One Hundred and One Ranch | city | Missouri | United States | 38.35 | -90.67 | 830 | |
| Ongo | city | Missouri | United States | 36.99 | -92.89 | 1669 | |
| Only | city | Missouri | United States | 37.92 | -92.95 | 1085 | |
| Opal | city | Missouri | United States | 37.02 | -93.77 | 1669 | |
| Opportunity Farms | city | Missouri | United States | 38.23 | -93.46 | 856 | |
| Oran | city | Missouri | United States | 37.09 | -89.66 | 357 | |
| Orange | city | Missouri | United States | 37.05 | -93.72 | 1669 | |
| Orchard Farm | city | Missouri | United States | 38.88 | -90.45 | 830 | |
| Orchid | city | Missouri | United States | 39.95 | -94.53 | 1049 | |
| Ore | city | Missouri | United States | 38.73 | -94.33 | 1000 | |
| Orearville | city | Missouri | United States | 39.17 | -93.07 | 830 | |
| Oregon | city | Missouri | United States | 39.99 | -95.14 | 1000 | |
| Origanna | city | Missouri | United States | 37.48 | -92.51 | 1200 | |
| Oriole | city | Missouri | United States | 37.44 | -89.54 | 830 | |
| Orla | city | Missouri | United States | 37.53 | -92.58 | 1200 | |
| Orleans (historical) | city | Missouri | United States | 37.52 | -93.52 | 997 | |
| Oronogo | city | Missouri | United States | 37.19 | -94.47 | 948 | |
| Orrick | city | Missouri | United States | 39.21 | -94.12 | 830 | |
| Orrsburg | city | Missouri | United States | 40.43 | -94.72 | 1151 | |
| Orrville | city | Missouri | United States | 38.64 | -90.66 | 830 | |
| Ortiz (historical) | city | Missouri | United States | 39.09 | -91.90 | 830 | |
| Osa | city | Missouri | United States | 36.90 | -93.63 | 1669 | |
| Osage Beach | city | Missouri | United States | 38.15 | -92.62 | 830 | |
| Osage Bend | city | Missouri | United States | 38.41 | -92.14 | 830 | |
| Osage Bluff | city | Missouri | United States | 38.44 | -92.22 | 830 | |
| Osage City | city | Missouri | United States | 38.55 | -92.03 | 830 | |
| Osage Heights | city | Missouri | United States | 37.98 | -93.81 | 830 | |
| Osage Hills | city | Missouri | United States | 38.57 | -90.45 | 830 | |
| Osborn | city | Missouri | United States | 36.58 | -90.21 | 314 | |
| Osborn | city | Missouri | United States | 39.75 | -94.36 | 1013 | |
| Osborn Crossing | city | Missouri | United States | 36.91 | -92.19 | 951 | |
| Oscar | city | Missouri | United States | 37.41 | -91.83 | 1669 | |
| Osceola | city | Missouri | United States | 38.05 | -93.70 | 830 | |
| Osgood | city | Missouri | United States | 40.20 | -93.35 | 830 | |
| Osiris | city | Missouri | United States | 37.67 | -94.04 | 967 | |
| Oskaloosa | city | Missouri | United States | 37.64 | -94.59 | 895 | |
| Oswald | city | Missouri | United States | 40.27 | -95.24 | 997 | |
| Otis | city | Missouri | United States | 36.61 | -89.60 | 288 | |
| Oto | city | Missouri | United States | 36.86 | -93.45 | 1000 | |
| Otterville | city | Missouri | United States | 38.70 | -93.00 | 830 | |
| Otto | city | Missouri | United States | 38.37 | -90.50 | 830 | |
| Overland | city | Missouri | United States | 38.70 | -90.36 | 830 | |
| Overton | city | Missouri | United States | 38.95 | -92.58 | 830 | |
| Ovid (historical) | city | Missouri | United States | 39.47 | -93.88 | 987 | |
| Oviet (historical) | city | Missouri | United States | 38.65 | -94.22 | 892 | |
| Owasco | city | Missouri | United States | 40.14 | -92.98 | 977 | |
| Owen (historical) | city | Missouri | United States | 38.92 | -90.87 | 830 | |
| Owenmont | city | Missouri | United States | 36.62 | -90.78 | 830 | |
| Owens | city | Missouri | United States | 37.22 | -92.40 | 1669 | |
| Owensville | city | Missouri | United States | 38.35 | -91.50 | 898 | |
| Owls Bend | city | Missouri | United States | 37.18 | -91.19 | 830 | |
| Owsley | city | Missouri | United States | 38.65 | -93.52 | 918 | |
| Oxford | city | Missouri | United States | 40.42 | -94.54 | 997 | |
| Oxly | city | Missouri | United States | 36.60 | -90.69 | 321 | |
| Oyer | city | Missouri | United States | 37.96 | -93.87 | 830 | |
| Ozark | city | Missouri | United States | 37.02 | -93.21 | 1174 | |
| Ozark Beach | city | Missouri | United States | 36.66 | -93.14 | 830 | |
| Ozark Junction | city | Missouri | United States | 38.17 | -92.12 | 898 | |
| Ozark Springs | city | Missouri | United States | 37.84 | -92.34 | 869 | |
| Ozark View | city | Missouri | United States | 38.58 | -90.46 | 830 | |
| Ozora | city | Missouri | United States | 37.86 | -90.03 | 830 |