The vast majority of the countries on earth became independent after 1800. Only 20 were independent before the start of the 19th century, a mere 10%. By 1900, only 49 or 25% of the world's countries of today were independent.
Many countries became independent following World War II when European powers granted independence to their vast colonial holdings, especially Africa.
Here are the independence days for every country, from the oldest to the youngest...
660 BCE - Japan
221 BCE - China
301 CE - San Marino
843 CE - France
976 CE - Austria
10th Century CE - Denmark
1001 - Hungary
1143 - Portugal
1206 - Mongolia
1238 - Thailand
1278 - Andorra
August 1, 1291 - Switzerland
1419 - Monaco
15th Century - Spain
1502 - Iran
June 6, 1523 - Sweden
January 23, 1579 - Netherlands
1650 - Oman
May 1, 1707 - United Kingdom
January 23, 1719 - Liechtenstein
1768 - Nepal
July 4, 1776 - United States of America
January 1, 1804 - Haiti
July 20, 1810 - Colombia
Sept. 16, 1810 - Mexico
Sept. 18, 1810 - Chile
May 14, 1811 - Paraguay
July 5, 1811 - Venezuela
July 9, 1816 - Argentina
July 28, 1821 - Peru
Sept. 15, 1821 - Costa Rica
Sept. 15, 1821 - El Salvador
Sept. 15, 1821 - Guatemala
Sept. 15, 1821 - Honduras
Sept. 15, 1821 - Nicaragua
May 24, 1822 - Ecuador
Sept. 7, 1822 - Brazil
August 6, 1825 - Bolivia
August 25, 1825 - Uruguay
1829 - Greece
October 4, 1830 - Belgium
1839 - Luxembourg
February 27, 1844 - Dominican Republic
July 26, 1847 - Liberia
March 17, 1861 - Italy
July 1, 1867 - Canada
January 18, 1871 - Germany
May 9, 1877 - Romania
March 3, 1878 - Bulgaria
1896 - Ethiopia
June 12, 1898 - Philippines
January 1, 1901 - Australia
May 20, 1902 - Cuba
November 3, 1903 - Panama
June 7, 1905 - Norway
Sept. 26, 1907 - New Zealand
May 31, 1910 - South Africa
November 28, 1912 - Albania
December 6, 1917 - Finland
November 11, 1918 - Poland
December 1, 1918 - Iceland
August 19, 1919 - Afghanistan
December 6, 1921 - Ireland
February 28, 1922 - Egypt
October 29, 1923 - Turkey
February 11, 1929 - Vatican City
Sept. 23, 1932 - Saudi Arabia
October 3, 1932 - Iraq
November 22, 1943 - Lebanon
August 15, 1945 - Korea, North
August 15, 1945 - Korea, South
August 17, 1945 - Indonesia
Sept. 2, 1945 - Vietnam
April 17, 1946 - Syria
May 25, 1946 - Jordan
August 14, 1947 - Pakistan
August 15, 1947 - India
January 4, 1948 - Burma
February 4, 1948 - Sri Lanka
May 14, 1948 - Israel
July 19, 1949 - Laos
August 8, 1949 - Bhutan
December 24, 1951 - Libya
November 9, 1953 - Cambodia
January 1, 1956 - Sudan
March 2, 1956 - Morocco
March 20, 1956 - Tunisia
March 6, 1957 - Ghana
August 31, 1957 - Malaysia
October 2, 1958 - Guinea
January 1, 1960 - Cameroon
April 4, 1960 - Senegal
May 27, 1960 - Togo
June 30, 1960 - Congo, Republic of the
July 1, 1960 - Somalia
July 26, 1960 - Madagascar
August 1, 1960 - Benin
August 3, 1960 - Niger
August 5, 1960 - Burkina Faso
August 7, 1960 - Cote d'Ivorie
August 11, 1960 - Chad
August 13, 1960 - Central African Republic
August 15, 1960 - Congo, Dem. Rep. of the
August 16, 1960 - Cyprus
August 17, 1960 - Gabon
Sept. 22, 1960 - Mali
October 1, 1960 - Nigeria
November 28, 1960 - Mauritania
April 27, 1961 - Sierra Leone
June 19, 1961 - Kuwait
January 1, 1962 - Samoa
July 1, 1962 - Burundi
July 1, 1962 - Rwanda
July 5, 1962 - Algeria
August 6, 1962 - Jamaica
August 31, 1962 - Trinidad and Tobago
October 9, 1962 - Uganda
December 12, 1963 - Kenya
April 26, 1964 - Tanzania
July 6, 1964 - Malawi
Sept. 21, 1964 - Malta
October 24, 1964 - Zambia
February 18, 1965 - Gambia, The
July 26, 1965 - Maldives
August 9, 1965 - Singapore
May 26, 1966 - Guyana
September 30, 1966 - Botswana
October 4, 1966 - Lesotho
November 30, 1966 - Barbados
January 31, 1968 - Nauru
March 12, 1968 - Mauritius
Sept. 6, 1968 - Swaziland
October 12, 1968 - Equatorial
June 4, 1970 - Tonga
October 10, 1970 - Fiji
March 26, 1971 - Bangladesh
August 15, 1971 - Bahrain
Sept. 3, 1971 - Qatar
November 2, 1971 - United Arab Emirates
July 10, 1973 - Bahamas
Sept. 24, 1973 - Guinea-Bissau
February 7, 1974 - Grenada
June 25, 1975 - Mozambique
July 5, 1975 - Cape Verde
July 6, 1975 - Comoros
July 12, 1975 - Sao Tome and Principe
Sept. 16, 1975 - Papua New Guinea
November 11, 1975 - Angola
November 25, 1975 - Suriname
June 29, 1976 - Seychelles
June 27, 1977 - Djibouti
July 7, 1978 - Solomon Islands
October 1, 1978 - Tuvalu
November 3, 1978 - Dominica
February 22, 1979 - Saint Lucia
July 12, 1979 - Kiribati
October 27, 1979 - Saint Vincent and the Grenadines
April 18, 1980 - Zimbabwe
July 30, 1980 - Vanuatu
January 11, 1981 - Antigua and Barbuda
Sept. 21, 1981 - Belize
Sept. 19, 1983 - Saint Kitts and Nevis
January 1, 1984 - Brunei
October 21, 1986 - Marshall Islands
November 3, 1986 - Micronesia, Federated States of
March 11, 1990 - Lithuania
March 21, 1990 - Namibia
May 22, 1990 - Yemen
April 9, 1991 - Georgia
June 25, 1991 - Croatia
June 25, 1991 - Slovenia
August 20, 1991 - Estonia
August 21, 1991 - Kyrgyzstan
August 24, 1991 - Russia
August 25, 1991 - Belarus
August 27, 1991 - Moldova
August 30, 1991 - Azerbaijan
Sept. 1, 1991 - Uzbekistan
Sept. 6, 1991 - Latvia
Sept. 8, 1991 - Macedonia
Sept. 9, 1991 - Tajikistan
Sept. 21, 1991 - Armenia
October 27, 1991 - Turkmenistan
November 24, 1991 - Ukraine
December 16, 1991 - Kazakhstan
March 3, 1992 - Bosnia and Herzegovina
January 1, 1993 - Czech Republic
January 1, 1993 - Slovakia
May 24, 1993 - Eritrea
October 1, 1994 - Palau
May 20, 2002 - East Timor
June 3, 2006 - Montenegro
June 5, 2006 - Serbia
February 17, 2008 - Kosovo
