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History of the Certificate of Naturalization, 1790–1956

The demand for proof of citizenship resulted in the creation of certificates of naturalization during the “Old Law” period of United States naturalization history (March 26, 1790–September 26, 1906). Government efforts to end naturalization fraud and ensure documentation of all naturalized citizens motivated the evolution of certificates throughout the “Certificate File (C-File)” period (September 27, 1906–March 31, 1956).

“Old Law” Period (March 26, 1790–September 26, 1906)

During the “Old Law” period, there was no federal oversight for the issuance of certificates of naturalization. Early naturalization laws allowed any "court of record" (municipal, county, state, or federal) to grant United States citizenship and did not even require courts to issue certificates.

Without statutory instruction or administrative oversight, certificates of naturalization issued prior to September 27, 1906, varied in size, shape, and design based on the clerk of court’s preference. The certificate’s contents also varied between courts with many omitting biographical information.

Many early certificates of naturalization were simply certified copies of the court orders conferring United States citizenship. By the mid-19th century, naturalization courts often provided more elaborate, pre-printed documents, but the quality and appearance of certificates of naturalization continued to vary significantly. 

Early certificates did not include important biographical information or security features. Without centralized content control, naturalization records often contained little more than the applicant’s name, the names of witnesses, and the country to which they renounced allegiance. Many courts’ certificates did not include a description of the person naturalized and were consequently easily transferable. The variation and absence of biometric information and security features made authenticating certificates of naturalization difficult, facilitating fraud.

Additionally, many certificates omitted names of family members who derived United States citizenship from the primary subject’s naturalization. Due to this, a large number of legitimate citizens are unnamed in the court records documenting their naturalization.

Courts did not keep copies of “Old Law” certificates of naturalization as insurance against loss of the original certificate by the naturalized citizen and/or destruction of the naturalization court’s records. The lack of provision for backup copies of naturalization records left both citizens and the government vulnerable to regional disasters which destroyed local court records. For example, the 1906 San Francisco earthquake and subsequent fire destroyed the city’s courthouses and homes. Many naturalized citizens' proof of citizenship burned, putting their rights as citizens in jeopardy, and the federal government faced many false claims to United States citizenship from persons claiming their naturalization prior to the catastrophe.

By the late 1800s, the effect of courts individually administering naturalization laws was evident in large numbers of naturalization fraud cases across the nation. The lack of uniformity in courts’ procedures and recordkeeping practices were factors in the problem, so Congress took steps to exert more control over the content, format, and issuance of certificates of naturalization.

“Certificate File (C-File)” period (September 27, 1906–March 31, 1956)

Congress passed the Basic Naturalization Act of 1906 to correct deficiencies in “Old Law” certificates of naturalization (and many other problems with the early naturalization system).  The law took effect September 27, 1906, founding the federal Naturalization Service, inaugurating the “Certificate File (C-File)” period, and transforming naturalization recordkeeping.

The Basic Naturalization Act of 1906 was Congress’ first real attempt at federal supervision of naturalization. It also marked the first time that the administration of the certificate of naturalization was specified by federal law. Beginning September 27, 1906, federal laws and regulations – enforced by an administrative oversight agency with stringent penalties for violations – required that all naturalization courts nationwide:

  • Issue a certificate of naturalization to every naturalized person (and name all members of the primary subject’s family who derived citizenship from the naturalization);
  • Create certificates of naturalization using standard forms distributed by the Naturalization Service which controlled the content, format, and quality of the records;
  • Submit a duplicate copy of every certificate of naturalization to the Naturalization Service for filing in a Certificate File (C-File); and
  • Only issue replacement or duplicate certificates with approval of the Naturalization Service.

These innovations achieved federal supervision of the courts’ naturalization activities. Standard forms imposed uniformity on certificates of naturalization issued on or after September 27, 1906, and collection of duplicates ensured a backup copy of certificates existed as protection against the loss of personal copies and/or courthouse records. Security features and uniform rules for issuing and replacing certificates also allowed the government to control, authenticate, and track certificates in circulation, increasing the records’ reliability as proof of identity and naturalization.

Every person naturalized between September 27, 1906, and March 31, 1956, has a Certificate File (C-File) with the United States Citizenship and Immigration Services (USCIS) (successor of the Immigration and Naturalization Service [INS]) containing a copy of their certificate of naturalization. When the Naturalization Service received the duplicate copy of a certificate of naturalization, it opened a unique C-File to hold the new citizen’s naturalization records. 

The Naturalization Service distributed three versions of its standard form certificate of naturalization during the “Certificate File (C-File)” period (1906–1956):

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On September 27, 1906, Form 2207 became the first standard form certificate of naturalization to be used by every naturalization court in the country. This ended variation between courts through controlled language and content requirements that ensured the inclusion of necessary biographical information (i.e., physical description of the rightful holder and names of family members who derived United States citizenship) that were frequently absent from many courts’ “Old Law” certificates.

The duplicate Form 2207 provided a copy for both the naturalized citizen and the Naturalization Service, and an index card for the naturalization court’s records. Clerks of court submitted the duplicate copy to the Naturalization Service which filed it in the naturalized citizen’s C-File. This provided insurance against loss of the original certificate by the naturalized citizen and/or destruction of the naturalization court’s records.

Printed on safety paper with sequential and tracked serial numbers, Form 2207 elevated certificates of naturalization to the status of “secure forms” (printed documents bearing inherent security features). These security features made certificates of naturalization far less transferable, combating naturalization fraud.

Form 2207 Certificates of Naturalization issued between September 27, 1906, and June 30, 1929, could include the following 

  • Biographical information about the rightful holder: name of holder; signature of holder; address of holder; country of former citizenship; and physical description of holder: age in years (when naturalized), height in feet and inches, color (race), complexion, eye color, hair color, and visible distinguishing marks. 
  • Biographical Information about the subject’s family: name, age, and place of residence of wife; and names, ages, and places of residence of minor children.
  • Security features: printed on safety paper; certificate number at top on left (C-Number, which corresponds to the Naturalization Service's C-File); certificates were consecutively numbered; and petition volume and number (facilitating location of the petition for naturalization in court records).
  • Court information: state and county of court; date, court, and location of naturalization; court's seal (only on original, not on the duplicate sent to Naturalization Service); court official's signature attesting to the facts listed on the certificate.

The Registry Act of 1929 brought changes to Form 2207 starting July 1, 1929.

Form 2207s issued after July 1, 1929, bear a signed photograph of the rightful holder and are slightly smaller than the earlier 1906 edition. The Registry Act also required the new Form 2207 to show any name change on the certificate.  

Post-Registry Act certificates of naturalization do not include the names of the subject’s spouse and minor children. Two changes in the naturalization laws made inclusion of this information on the certificate unnecessary (but it still appears on the petition for naturalization). First, the Married Women’s Citizenship Act (Cable Act) ended derivation of citizenship by marriage on September 22, 1922. Second, the Registry Act authorized the Naturalization Service to issue certificates of citizenship in the name of persons deriving citizenship (i.e., children of the naturalized citizen). Due to these changes, names of family members were no longer required on the primary subject’s naturalization certificate to prove their citizenship status.

The Registry Act of 1929 also authorized the Naturalization Service to begin issuing certificates of citizenship to persons receiving United States citizenship after birth but not receiving certificates of naturalization from a naturalization court (e.g., persons deriving citizenship or repatriating). 

The Registry Act also empowered the Naturalization Service to issue replacement certificates of naturalization when the original was lost, mutilated, or destroyed. Thereafter, courts no longer issued replacement certificates (even for “Old Law” naturalizations issued before September 27, 1906). 

The Naturalization Service created a new sub-series of C-Files to hold certificates of citizenship and related administrative records. Many of the persons documented by certificates of citizenship may not appear in court records.

The Naturalization Service united with the Immigration Service to form the Immigration and Naturalization Service (INS) in 1933. The INS transferred from the Department of Labor to the Justice Department in 1940. The Naturalization Service renumbered and reformatted its forms to reflect this restructuring and bring its certificate of naturalization into compliance with the requirements of the Nationality Act of 1940.

The Form N-550 moved the certificate number to the top right of the certificate and replaced “Department of Labor” with “Department of Justice” on the bottom. The new form also printed “DUPLICATE” on top left of the Naturalization Service copy. The biggest change was the addition of a statement that "It is a violation of the U.S. Code (and punishable as such) to copy, print, photograph, or otherwise illegally use this certificate.”  

INS continued to use Form N-550 with many amendments and new versions issued. Beginning April 1, 1956, creation of C-Files formally ended, and all certificates of naturalization (and all immigration and naturalization records) went into an individual’s Alien File (A-File). This practice continues today. 

Today C-Files are in the custody of the United States Citizenship and Immigration Services (USCIS), and can be requested through the USCIS Genealogy Program.  

Naturalization acts (both before and after the Registry Act of 1929) referred to “Certificates of Naturalization” as “Certificates of Citizenship.”

In practice, the term “Certificate of Naturalization” (presently tied to Form N-550 and its variants) was used for those who completed the traditional naturalization process and the term “Certificate of Citizenship” (presently tied to Form N-560 and its variants) was used for derivative citizenship.

Sometimes the N-550 certificate of naturalization had a heading that read “Certificate of Citizenship.” For stretches in the 1930s, for example, the certificate of naturalization read “Certificate of Citizenship,” and there were cases where an individual lost an earlier N-550 that said “Certificate of Naturalization” and received a replacement that said “Certificate of Citizenship.”  

The certificate heading only reflects when the document was printed and what design was being used at that time. The heading does not indicate anything about the naturalization itself. The form number on the certificate and the text on the certificate will indicate if it is a derivative certificate.

Researching Certificates of Naturalization

In most cases, the National Archives will not have a copy of the certificate of naturalization. Two copies of the certificate were created after September 26, 1906 – one given to the petitioner as proof of citizenship, and one forwarded by the courts to the Immigration and Naturalization Service (INS).

Certificates of naturalization were issued by the federal courts until October 1991 when naturalization became an administrative function under the INS.

INS records are now overseen by the United States Citizenship and Immigration Services (USCIS). USCIS maintains duplicate copies of naturalization records (including certificates) created September 27, 1906–March 31, 1956 within Certificate Files (C-Files). Beginning April 1, 1956, INS began filing all naturalization records in a subject’s Alien File (A-File). C-Files can be requested through the USCIS Genealogy Program

If you are a naturalized citizen seeking your own documentation, you can place a Freedom of Information Act (FOIA) request to USCIS to obtain a copy of your records and/or request a replacement certificate of citizenship from USCIS.