Kargopolsky District subordinated to the central administration of Northern Krai. In 1936, the krai was transformed into Northern Oblast. In 1937, Northern Oblast itself was split into Arkhangelsk Oblast and Vologda Oblast. Kargopolsky District remained in Arkhangelsk Oblast ever since. The district is almost exclusively located in the basin of the Onega River, which is the biggest river in the district, and belongs to the basin of the White Sea. The source of the Onega is Lake Lacha, which is the biggest lake in the district. The northeastern shore of Lake Vozhe, also in the basin of the Onega, belongs to Kargopolsky
Primorsky District, Arkhangelsk Oblast first-level administrative division of Russia kept changing. In 1930, the okrug was abolished, and the district was subordinated to the central administration of Northern Krai. In 1936, the krai was transformed into Northern Oblast. In 1937, Northern Oblast itself was split into Arkhangelsk Oblast and Vologda Oblast. Primorsky District remained in Arkhangelsk Oblast ever since. The location of the administrative center of the district was moved several times until Arkhangelsk finally became the center. On December 17, 1940, Belomorsky District was established on the Onega Peninsula, in the areas which previously were parts of Primorsky and Onezhsky Districts. The administrative