Latvian language
Upper Latvian dialect is spoken in Eastern Latvia. It is set apart from rest of the Latvian by number of phonetic differences. The dialect has two main varieties – Selonian and Non-Selonian. There is a standard language, the Latgalian language, which is based on deep Non-Selonian varieties spoken in south of Latgale. The term "Latgalian" is sometimes also applied to all Non-Selonian varieties or even the whole dialect. However, it is unclear if it is accurate to use the term for any varieties besides the standard language. While the term may refer to varieties spoken in Latgale or by Latgalians, not all speakers identify as speaking Latgalian, for example, speakers of deep Non-Selonian varieties in Vidzeme explicitly deny speaking Latgalian.
Russians in Latvia
Russians were the main ethnic group in the USSR both in number and in political influence. Under the conditions of Soviet Latvia, Russian culture dominated the whole non-Latvian population of the Republic. The Russian language also formed a new group of Russian-speaking Belarusians, Ukrainians, Poles, Jews and Germans of Latvia. In the period of 1959–1979 the number of ethnic Russians in Latvia increased by 47%, but the number of non-Russians considering Russian their mother tongue increased by 78%. A highly developed infrastructure was developed in Latvia on the basis of the Russian language: a broad system of secondary and higher education, science and mass media.