Sovereign States
editA
edit- Abkhazia - Socialist Soviet Republic of Abkhazia (from March 31)
- Afghanistan - Emirate of Afghanistan
- Albania - Principality of Albania
- Andorra - Principality of Andorra
- Argentina - Argentine Republic
- Armenia - Armenian Socialist Soviet Republic
- File:Flag of Asir.svg Asir - Emirate of Asir
- Australia - Commonwealth of Australia
- Austria - Federal State of Austria
- Azerbaijan - Azerbaijan Socialist Soviet Republic
B
edit- Belgium - Kingdom of Belgium
- Bolivia - Republic of Bolivia
- Brazil - Republic of the United States of Brazil
- Bulgaria - Kingdom of Bulgaria
C
edit- Canada - Dominion of Canada
- Central America - Federation of Central America (from October 1)
- Chile - Republic of Chile
- China - Republic of China
- Colombia - Republic of Colombia
- Costa Rica - Republic of Costa Rica
- Cuba - Republic of Cuba
- Czechoslovakia - Czechoslovak Republic
D
edit- Danzig - Free City of Danzig
- Denmark - Kingdom of Denmark
- Dominican Republic
E
edit- Ecuador - Republic of Ecuador
- El Salvador - Republic of El Salvador (to October 1)
- Estonia - Republic of Estonia
- Ethiopia - Ethiopian Empire
F
editG
edit- Georgia - Democratic Republic of Georgia (to February 11)
- Germany - German Reich
- Greece - Kingdom of Greece
- Guatemala - Republic of Guatemala (to October 1)
H
edit- Ha'il - Emirate of Ha'il (to November 2)
- Haiti - Republic of Haiti
- Hejaz - Kingdom of Hejaz
- Honduras - Republic of Honduras (to October 1)
- Hungary - Kingdom of Hungary
I
editJ
edit- Japan - Empire of Japan
L
edit- Latvia - Republic of Latvia
- Liberia - Republic of Liberia
- Liechtenstein - Principality of Liechtenstein
- Lithuania - Republic of Lithuania
- Luxembourg - Grand Duchy of Luxembourg
M
edit- Mexico - United Mexican States
- Monaco - Principality of Monaco
- Mongolia - Mongolian People's Government (from July 11)
N
edit- Nejd
- Emirate of Nejd (to August 22)
- Sultanate of Nejd (from August 22)
- Netherlands - Kingdom of the Netherlands
- Newfoundland - Dominion of Newfoundland
- New Zealand - Dominion of New Zealand
- Nicaragua - Republic of Nicaragua
- Norway - Kingdom of Norway
O
edit- Ottoman Empire - Sublime Ottoman State
P
edit- Panama - Republic of Panama
- Paraguay - Republic of Paraguay
- Persia - Persian Empire
- Peru - Peruvian Republic
- Poland - Republic of Poland
- Portugal - Portuguese Republic
R
editS
edit- San Marino - Most Serene Republic of San Marino
- Serbs, Croats and Slovenes - Kingdom of Serbs, Croats, and Slovenes
- Siam - Kingdom of Siam
- South Africa - Union of South Africa
- Spain - Kingdom of Spain
- Sweden - Kingdom of Sweden
- Switzerland - Swiss Confederation
U
edit- United Kingdom - United Kingdom of Great Britain and Ireland
- United States - United States of America
- Uruguay - Eastern Republic of Uruguay
V
edit- Venezuela - United States of Venezuela
Y
edit- Yemen - Mutawakkilite Kingdom of Yemen
Other states
edit- File:Serbia flag large.png Baranya-Baja - Serb-Hungarian Baranya-Baja Republic (from August 14 to August 25)
- Bottleneck - Free State Bottleneck
- Bukharan - Bukharan People's Soviet Republic
- Byelorussia - Byelorussian Socialist Soviet Republic
- Central Lithuania - Republic of Central Lithuania
- Far Eastern Republic
- Georgia, Soviet - Socialist Soviet Republic of Georgia (from February 11)
- Gilan - Persian Socialist Soviet Republic (to September)
- Ireland - Irish Republic
- Khorezm - Khorezm People's Soviet Republic
- Labin - Labin Republic (from March 2 to April 8)
- File:Lajtabánság zászlaja.gif Lajtabánság - Banat of Leitha (from October 4 to November 5)
- Mirdita - Republic of Mirdita (from July 17 to November 20)
- Mongolia - Boghda Khaanate of Mongolia
- North Caucasian Emirate
- Rif - Confederal Republic of the Tribes of the Rif (from September 18)
- Tannu Tuva - People's Republic of Tannu Tuva (from August 14)
- Tavolara - Kingdom of Tavolara
- Tibet
- Ukraine, Soviet - Ukrainian Socialist Soviet Republic
League of Nations Mandates
edit- Mesopotamia - British Mandate of Mesopotamia (administered by the United Kingdom)
- Nauru (administered by Australia, New Zealand and the United Kingdom)
- New Guinea - Territory of New Guinea (administered by Australia)
- South Pacific Mandate (administered by Japan)
- Western Samoa (administered by New Zealand)