Бежецкий район
On July 12, 1929 the governorates and uyezds were abolished. Sonkovsky District, with the administrative center in the settlement of Sonkovo, was established within Bezhetsk Okrug of Moscow Oblast. On July 23, 1930, the okrugs were abolished, and the districts were directly subordinated to the oblast. On January 29, 1935 Kalinin Oblast was established, and Sonkovsky District was transferred to Kalinin Oblast. On February 13, 1963, during the abortive Khrushchyov administrative reform, Sonkovsky District was merged into Bezhetsky District, but on January 12, 1965 it was re-established. In 1990, Kalinin Oblast was renamed Tver Oblast.