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Decennial Census Records


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An example of a 1930 Soundex Card.
Photo courtesy of the National Archives.

The Soundex is a coded surname index (using the first letter of the last name and three digits) based on the way a name sounds rather than the way it's spelled. Surnames that sound the same but are spelled differently - such as Smith and Smyth - have the same code and are filed together. This system was developed to make it easier to find a particular name even though it may have been spelled (or misspelled, as was more often the case) a variety of ways.

The decennial census Soundex system began as a project of the Franklin D. Roosevelt Administration's Works Progress Administration (WPA). Because many states did not have uniform systems for registering births, the Soundex indexes were originally prepared to assist the Census Bureau in finding records for people who needed official proof of age.

The Soundex is available on microfilm at the National Archives and its Regional Archives System, the Church of Latter-Day Saints Family History Library, and larger public libraries throughout the county. Once you locate an ancestor in the Soundex cards, you be able to make note of the enumeration district, city, county, state, and page number where your ancestor is listed. Then you can order the microfilm of the original census record, to photocopy for your family history records.

For more information:

To learn more about the history of Soundex and how to use the system to access genealogy records, visit the following Web Sites:

Several Web Sites have developed Soundex converters to assist researchers with the conversion of a surname to the Soundex Indexing Code. One such Web site is :

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Source: U.S. Census Bureau | Census History Staff | Last Revised: August 14, 2023