Ohio 41,577
Oregon 29,182
Ontario 25,009
Oklahoma 15,849
Oceania 11,001
Outer space 5,679
Oxford 5,033
OECD countries 4,978
Oman 4,355
Odisha 3,168
Orient 2,596
Okinawa-ken 2,481
Oxford (England) 2,293
Ohio River Valley 2,165
Okinawa-ken (Japan) 2,087
Orissa 2,062
Osaka 1,871
Oaxaca (State) 1,821
Orange County 1,708
Oakland 1,642
Ohio River 1,560
Oaxaca (Mexico : State) 1,397
Odisha (India) 1,382
Odesa 1,332
Osaka (Japan) 1,311
Orissa (India) 1,249
Osmanisches Reich 1,226
Odesa (Ukraine) 1,206
Oslo 1,055
Oaxaca 1,043
Oakland (Calif.) 1,016
Oxfordshire 899
Ottawa 885
Oxfordshire (England) 880
Okinawa Island 853
Oregon Territory 850
Osteuropa 788
Ouganda 760
Oregon National Historic Trail 752
Orkney (Scotland) 728
Ozark Mountains 670
Omaha 644
Old Northwest 640
Orkney 603
Oslo (Norway) 569
Österreich 554
Omaha (Neb.) 548
Ostfriesland 544
Odessa 541
Orange County (Calif.) 527
Ostfriesland (Germany) 508
Osaka (Prefecture) 499
Ottawa (Ont.) 485
Oahu 478
Oldenburg 466
Okayama-ken 464
Ostasien 464
Okinawa Island (Japan) 459
Oceania Region 452
Ostroh 451
Oklahoma City 448
Okayama-ken (Japan) 445
Osaka (Japan : Prefecture) 442
Occident 425
Onondaga County 414
Ohio River Region 398
Océanie 395
Oświęcim 379
Oneida County 357
Ontario, Lake (N.Y. and Ont.) 356
Old Southwest 335
Oświęcim 328
Oudh (India) 324
Omsk 322
Orvieto 309
Oklahoma City (Okla.) 308
Onondaga County (N.Y.) 291
Orange County (N.Y.) 291
Oudh 289
Orenburgskai︠a︡ oblastʹ (Russia) 287
Ontario, Northern 286
Orange 284
Ostia (Extinct city) 284
Oldenburg (Germany) 276
Oran 275
Oran (Algeria) 272
Orlovskai︠a︡ oblastʹ 272
Osnabrück (Germany) 272
Oder-Neisse Line (Germany and Poland) 270
Oaxaca de Juárez (Mexico) 267
Orléans 267
Orléans (France) 267
Orlando 266
Osnabrück 266
Oberpfalz 264
Omsk (Russia) 264
Olomouc 263
Olympic National Park (Wash.) 263
Oneida County (N.Y.) 254
Ozark Mountains Region 253