The National Archives of Latvia is the largest archival institution in the Baltic region, with approximately 20 million archival units dating from the 13th century onward. The National Archives comprise several specialized repositories, two of which are particularly important for research on Russian history.

The first is the Latvian State Historical Archives (LVVA), whose holdings primarily document the imperial period. The archive preserves more than six million records relating to the political, economic, and cultural history of present-day Latvia, covering the years 1220-1945. Particularly valuable fonds include the following.

• Chancellery of the governor-general of Livonia, Estonia, and Courland (1776-1917)
• Livonia Governorate administration: Senate records, prosecutorial supervision, passport, and prison records (1797-1917)
• Riga police administration (1787-1917)
• Chief administration for press affairs and the Riga press inspector (1865-1915)
• Medical and veterinary departments of the Livonia Governorate administration (1865-1918)

Documents can be located through the archive's online database, which contains descriptions of 5,935 fonds, 18,204 inventories, and 494,253 archival files. Researchers who do not know the reference numbers of relevant files can search the database using keywords.

Particular attention should also be paid to Raduraksti, a digital platform launched by the LVVA in 2010. It provides access to databases for genealogical and demographic research, including the following.

• Parish registers from Livonia and Courland
• Nominal tax registers
• Materials from the 1897 Russian Empire census covering the Courland, Livonia, and Vitebsk governorates
• Riga house registers and a passport database
• Database of University of Latvia students (1919-1944) with biographical information and digitized archival documents

The second major repository is the Latvian State Archives (LVA). It is the principal institution for documents relating to the Soviet period in Latvia (1940-1941 and 1945-1991). The archive preserves records of the highest state authorities, personal papers, the archives of the Communist Party of Latvia, and KGB files on individuals subjected to political persecution.

One of the most extensive digitized collections of KGB documents in Eastern Europe is available through the LVA. Comparable materials are now effectively inaccessible in Russia, even for Russian citizens. After registering on the portal, researchers receive full access to the following.

• Card indexes of KGB agent networks and personal files of collaborators
• Operational files, including officers' and agents' reports, transcripts of telephone intercepts, and intercepted correspondence
• Records of KGB front organizations, including societies for cultural relations, peace committees, and similar organizations
• Telephone directories and administrative records of the leadership of the Latvian SSR state security organs
• KGB counterintelligence handbook

Another important LVA resource is the Database of Deported Latvian Residents in 1941-1953. It is based on investigation case files, registration cards, and records of the NKVD, NKGB, Ministry of Internal Affairs, and KGB of the Latvian SSR. Information is organized by locality within Latvia and by the surnames of deported individuals.

Outside of the National Archives of Latvia, special mention should be made of the Latvian State Archive of Audiovisual Documents. Among its most valuable holdings are newsreels, photographs, and sound recordings documenting all-Union events and Soviet propaganda. The catalog currently contains 11,220 films, 147,414 photographs, and 1,888 audio recordings, with new materials added on a regular basis.

Another indispensable resource is Periodika, a project of the National Library of Latvia. Since 2008, the library has been building this digitized collection of historical newspapers and periodicals. Riga was one of the principal centers of the Russian-language press, first within the Russian Empire and later in independent Latvia. Digitized publications from the 19th and early-20th centuries include Rizhskiy Vestnik, Kurlyandskiye Gubernskiye Vedomosti, and Rizhskoye Obozreniye. The collection also includes Soviet-era newspapers and official publications, including Krasnoye Znamya, Golos naroda, and Vedomosti Prezidiuma Verkhovnogo Soveta LSSR, among others.