Sovereign States
editA
edit- Afghanistan - Emirate of Afghanistan
- Albania - Principality of Albania
- Andorra - Principality of Andorra
- Argentina - Argentine Republic
- Armenia
- Democratic Republic of Armenia (to November 29)
- Armenian Socialist Soviet Republic (from November 29)
- File:Flag of Asir.svg Asir - Emirate of Asir
- Asir, Upper - Emirate of Upper Asir (to August)
- Australia - Commonwealth of Australia
- Austria - Federal State of Austria
- Azerbaijan
- Azerbaijan Democratic Republic (to April 28)
- Azerbaijan Socialist Soviet Republic (from April 28)
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
- Chile - Republic of Chile
- China - Republic of China
- Colombia - Republic of Colombia
- Costa Rica - Republic of Costa Rica
- Cuba - Republic of Cuba
- Czechoslovakia
- Czecho-Slovak Republic (to 1920)
- Czechoslovak Republic (from 1920)
D
edit- Danzig - Free City of Danzig (from January 10)
- Denmark - Kingdom of Denmark
- Dominican Republic
E
edit- Ecuador - Republic of Ecuador
- El Salvador - Republic of El Salvador
- Estonia - Republic of Estonia
- Ethiopia - Ethiopian Empire
F
edit- Finland - Republic of Finland
- Fiume - Free State of Fiume (from November 12)
- France - French Republic
G
edit- Georgia - Democratic Republic of Georgia
- Germany - German Reich
- Greece - Kingdom of Greece
- Guatemala - Republic of Guatemala
H
edit- Ha'il - Emirate of Ha'il
- Haiti - Republic of Haiti
- Hejaz - Kingdom of Hejaz
- Honduras - Republic of Honduras
- Hungary - Kingdom of Hungary (from March 1)
I
editJ
edit- Japan - Empire of Japan
L
edit- Latvia (Disputed between two governments to January 13)
- Liberia - Republic of Liberia
- Liechtenstein - Principality of Liechtenstein
- Lithuania - Republic of Lithuania
- Luxembourg - Grand Duchy of Luxembourg
M
editN
edit- Nejd - Emirate of Nejd
- 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- Alash - Alash Autonomy (to August 26)
- Bottleneck - Free State Bottleneck
- Bukharan - Bukharan People's Soviet Republic (from October 8)
- Byelorussia - Byelorussian Socialist Soviet Republic (from August 1)
- Carnaro - Italian Regency of Carnaro (from September 8 to December 30)
- Central Lithuania - Republic of Central Lithuania (from October 12)
- Don - Don Republic (to 1920)
- Far Eastern Republic (from April 6)
- Galicia - Galician Socialist Soviet Republic (from July 8 to September 21)
- Gilan - Persian Socialist Soviet Republic (from June)
- Ireland - Irish Republic
- Khiva (to April 30), Khorezm (from April 30)
- Khanate of Khiva (to April 30)
- Khorezm People's Soviet Republic (from April 30)
- Kuban - Kuban People's Republic
- Lemko-Rusyn - Lemko-Rusyn Republic (to March)
- Mongolia - Boghda Khaanate of Mongolia
- North Caucasian Emirate
- Northern Caucasus - Mountainous Republic of the Northern Caucasus (to June)
- North Ingria - Republic of North Ingria (to December 20)
- Siberia, Autonomous - Provisional Government of Autonomous Siberia (to February 7)
- 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 from April 10)
- Nauru (administered by Australia, New Zealand and the United Kingdom from December 17)
- New Guinea - Territory of New Guinea (administered by Australia from December 17)
- South Pacific Mandate (administered by Japan from 1920)
- Western Samoa (administered by New Zealand from December 17)