Slovakia
1 January 1993 (Czechoslovakia split into the Czech
Republic and Slovakia)

Slovenia
25 June 1991 (from Yugoslavia)

Solomon Islands
7 July 1978 (from UK)

Somalia
1 July 1960 (from a merger of British Somaliland, which
became independent from the UK on 26 June 1960, and Italian
Somaliland, which became independent from the Italian-administered
UN trusteeship on 1 July 1960, to form the Somali Republic)

South Africa
31 May 1910 (Union of South Africa formed from four
British colonies: Cape Colony, Natal, Transvaal, and Orange Free
State); 31 May 1961 (republic declared) 27 April 1994 (majority rule)

Spain
the Iberian peninsula was characterized by a variety of
independent kingdoms prior to the Muslim occupation that began in
the early 8th century A.D. and lasted nearly seven centuries; the
small Christian redoubts of the north began the reconquest almost
immediately, culminating in the seizure of Granada in 1492; this
event completed the unification of several kingdoms and is
traditionally considered the forging of present-day Spain

Sri Lanka
4 February 1948 (from UK)

Sudan
1 January 1956 (from Egypt and UK)

Suriname
25 November 1975 (from the Netherlands)

Svalbard
none (territory of Norway)