South Dakota Naturalization and Citizenship
In the territorial era, naturalization proceedings were handled by the U.S. district courts. For information, contact the National Archives—Central Plains Region at Kansas City.
After statehood in 1889, the clerk of the circuit court in each county was authorized to keep all naturalization records. You can obtain copies of declarations and petitions from the clerk's office.
For naturalization records after September 1906, contact the National Archives—Central Plains Region at Kansas City or the local office of the United States Citenship and Immigration Services (formerly INS). The Family History Library has many county naturalization records from the district and circuit courts.