Understanding the Soundex
Use of the 1920, 1910, 1900, and 1880 censuses are aided by a unique microfilmed card index to some of them. It is known as the Soundex. In it, surnames are coded from the way they sound rather than how they are spelled.
The Soundex code consists of a letter (always the first letter of the surname) and three numbers. Numbers are assigned according to the following table:
| Number | Represents Letter |
| 1 | B P F V |
| 2 | C S G J K Q X Z |
| 3 | D T |
| 4 | L |
| 5 | M N |
| 6 | R |
Follow the following rules when coding your surnames:
In coding your surname, disregard these letters: A, E, I, O, U, W, Y, and H.
Double letters are treated as one letter.
On short names, if there are less than three numbers, add zeroes to the end of the coding.
On long names, once you have three digits, disregard any additional ones.
If your surname has a prefix such as van, Van, Von, D', de, De, dela, Di, du, or Le, code it both with and without the prefix because it might be listed under either code.
Mc and Mac are not considered prefixes in the Soundex.
Your surname may have different letters that are side-by-side but have the same number on the above Soundex table. For example, in the surname Jackson, 2 is the number for C, K and S. In such cases, these letters are treated as one letter. Jackson is Soundexed as J250, not J222.
You can find Soundex codes from any census as indicated by the following table:
| Year | Soundex |
| 1880 | The 1880 census has Soundex codes only for households that had children ages 10 and under. If your ancestors were a newly married couple in 1880 with no children, or were an older couple whose children were ages 11 and older, you probably will not find them in the 1880 Soundex and will need to search the actual county's enumeration. |
| 1890 | Most of the 1890 census was destroyed by fire. |
| 1900 | The 1900 census has Soundex codes for all states. |
| 1910 | The 1910 census has Soundex codes or Miracodes indexed for only 21 states (The Miracode is a slightly modified version of the Soundex. It uses the same phonetic code and abbreviations as the Soundex but Miracode cards list the visitation numbers assigned by the enumerators, while Soundex cards show the page and line numbers on the appropriate census schedules.) Those 21 states are: Alabama, Arkansas, California, Florida, Georgia, Illinois, Kansas, Kentucky, Louisiana (uses both Soundex and Miracode), Michigan, Mississippi, Missouri, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, and West Virginia. |
| 1920 | The 1920 census has Soundex codes for all states. |
Use indexes and Soundexes with caution. There are errors and omissions in all of them. If you know (or strongly suspect) your family was living in a particular county, read the entire census for that locality. If you find any errors or ommissions in the Soundex lists on this site, please email me.
