Ohio 41,522
Oregon 29,154
Ontario 24,973
Oklahoma 15,821
Oceania 10,987
Outer space 5,668
Oxford 5,007
OECD countries 4,983
Oman 4,323
Odisha 3,155
Orient 2,598
Okinawa-ken 2,479
Oxford (England) 2,290
Ohio River Valley 2,160
Okinawa-ken (Japan) 2,083
Orissa 2,065
Osaka 1,865
Oaxaca (State) 1,819
Orange County 1,707
Oakland 1,635
Ohio River 1,560
Oaxaca (Mexico : State) 1,396
Odisha (India) 1,374
Osmanisches Reich 1,331
Odesa 1,330
Osaka (Japan) 1,307
Orissa (India) 1,250
Odesa (Ukraine) 1,202
Oslo 1,054
Oaxaca 1,047
Oakland (Calif.) 1,013
Oxfordshire 897
Ottawa 881
Oxfordshire (England) 880
Okinawa Island 850
Oregon Territory 850
Osteuropa 815
Oregon National Historic Trail 752
Orkney (Scotland) 728
Ouganda 726
Ozark Mountains 668
Omaha 644
Old Northwest 639
Orkney 605
Oslo (Norway) 568
Österreich 565
Omaha (Neb.) 548
Ostfriesland 545
Odessa 539
Orange County (Calif.) 527
Ostfriesland (Germany) 508
Osaka (Prefecture) 499
Ostasien 491
Ottawa (Ont.) 483
Oahu 475
Oldenburg 466
Okayama-ken 463
Okinawa Island (Japan) 459
Oceania Region 453
Ostroh 451
Oklahoma City 449
Okayama-ken (Japan) 444
Osaka (Japan : Prefecture) 441
Onondaga County 414
Occident 402
Ohio River Region 398
Océanie 386
Oświęcim 377
Oneida County 356
Ontario, Lake (N.Y. and Ont.) 356
Old Southwest 335
Oświęcim 329
Oudh (India) 324
Omsk 321
Oklahoma City (Okla.) 308
Orvieto 306
Orange County (N.Y.) 293
Onondaga County (N.Y.) 292
Oudh 289
Ontario, Northern 286
Orenburgskai︠a︡ oblastʹ (Russia) 286
Ostia (Extinct city) 282
Orange 281
Oldenburg (Germany) 275
Oran 274
Oran (Algeria) 272
Osnabrück (Germany) 272
Orlovskai︠a︡ oblastʹ 271
Oaxaca de Juárez (Mexico) 267
Oder-Neisse Line (Germany and Poland) 267
Orléans 267
Orléans (France) 267
Osnabrück 265
Omsk (Russia) 264
Orlando 264
Oberpfalz 263
Olympic National Park (Wash.) 263
Olomouc 262
Oneida County (N.Y.) 253
Ozark Mountains Region 253