| 21 Jul 1940 |
Latvia is declared a Soviet Socialist Republic in accordance with a declaration passed by the People's Assembly (Tautas Saeima) on 21 Jul 1940 (Valdības Vēstnesis, No. 163, 22 Jul 1940, p. 3) |
| 21 Jul 1940 - 4 May 1990 |
Latvijas Padomju Sociālistiskā Republika = (to 6 Oct 1988) Latvijskaja Sovetskaja Socialističeskaja Respublika (Латвийская Советская Социалистическая Республика) | Latvian Soviet Socialist Republic |
| 21 Jul 1940 |
Latvia applied for accession to the Union of Soviet Socialist Republics in accordance with a declaration passed by the People's Assembly (Tautas Saeima) on 21 Jul 1940 (Valdības Vēstnesis, No. 163, 22 Jul 1940, p. 3) |
| 5 Aug 1940 |
Latvia is admitted to the Union of Soviet Socialist Republics in accordance with a law passed by the Supreme Council of the Union of the Soviet Socialist Republics on 5 Aug 1940 (USSR Supreme Council Proceedings 1940 – 7th Session, pp. 119-121, 187) |
| 6 Oct 1988 |
Latvian is declared state language in accordance with a law passed by the Supreme Council (Augstākā Padome) 6 Oct 1988 (Latvian SSR Supreme Council Records, No. 41, 13 Oct 1988; Cīņa, No. 233, 11 Oct 1988, p. 4) |
| 28 Jul 1989 |
Latvia is proclaimed a sovereign state in accordance with a declaration passed by the Supreme Council (Augstākā Padome) on 28 Jul 1989 (Cīņa, No. 174, 29 Jul 1989, p. 1) |
