North Dakota Naturalization and Citizenship
Naturalization records have been filed in the county and district courts of the state. You can write to the clerk of the court and request a search of indexes to certificates of arrival, declarations, petitions, and final naturalization papers. Due to population changes, the jurisdictions of the courts have varied from time to time.
The Family History Library has acquired district court records for each county in North Dakota. These records often go up to the 1940s and 1950s. On the state level, circuit court records have also been acquired. Search the Family History Library Catalog for specific film numbers.
If you do not find the naturalization record you are seeking in the catalog, you may contact the National Archives and Records Administration—Rocky Mountain Region or the local office of the United States Citizenship and Immigration Services (formerly INS), for records after September 1906.
The National Archives—Rocky Mountain Region: 
The National Archives—Central Plains Region (Kansas City) has a few of the U.S. District Court records from 1892 to 1906, http://www.archives.gov/central-plains/kansas-city/