Dear Mr. Ekonomou,
Thank you for posting your request on History Hub!
Foreign citizenship is only renounced/forfeited if the individual completes the naturalization process in the United States. Immigration into the U.S. does not equate to a change in citizenship status. If your grandfather may have naturalized, then you may wish to submit a request to the National Archives facility that maintains records for the Federal courts in the state where his grandfather resided.
It may also be worthwhile to submit a request to obtain a Certification of Non-Existence of a Record of Naturalization from the U.S. Citizenship and Immigration Services (USCIS). To request a certificate of non-existence of a specific record, write directly to the USCIS Records Services at the address below. Your request must include the immigrant’s information:
- Name (including all variants and aliases)
- Date of birth
- Place of birth
- As much information as possible about when and where the immigrant arrived in or lived in the United States. The names of immediate immigrant relatives can also be helpful.
If the immigrant’s birth date is less than 100 years before the request date, you must also include a copy of their birth or death certificate. Please mail your request to U.S. Citizenship and Immigration Services; ATTN: Certification of Non-Existence; 1200 First Street, NE, 2nd Floor; Washington, DC 20529-2204.
Note further that the USCIS does not accept original requests by email and will only mail certificates to U.S. addresses. If you have questions, email firstname.lastname@example.org.
We hope this is helpful. Best of luck with your family research!
[Information provided by Elizabeth Burnes, Subject Matter Expert]