Overview of Soundex

This document is largely based on a the following publication, with corrections to better match usage in actual US Census indices:

The 1790-1890 Federal Population Censuses:
Catalog of National Archives Microfilm (Part 1)

National Archives Trust Fund Board
National Archives and Records Administration
Washington, DC

First applied to the 1880 census, Soundex is a phonetic index, not a strictly alphabetical one. Its key feature is that it codes surnames (last names) based on the way a name sounds rather than on how it is spelled. For example, surnames that sound the same but are spelled differently, like Smith and Smyth, have the same code and are indexed together. The intent was to help researchers find a surname quickly even though it may have received different spellings. If a name like Cook, though, is spelled Koch or Faust is Phaust, a search for a different set of Soundex codes and cards based on the variation of the surname’s first letter is necessary.

To use Soundex, researchers must first code the surname of the person or family in which they are interested. Every Soundex code consists of a letter and three numbers, such as B-536, representing names such as Bender. The letter is always the first letter of the surname, whether it is a vowel or a consonant.

Disregard the remaining vowels (A, E, I, O, and U) as well as W, Y, and H. Assign numbers to the next three consonants of the surname according to the coding guide included in table 1, but note the exceptions discussed later. Disregard any remaining consonants. If there are not three consonants following the initial letter, use zeroes to complete the three-digit code. A name yielding no code number, such as Lee, would thus be L-000. A name with only one code number, such as Cook, would be C-200. Further discussion will use this name and code as examples.

Most surnames can be coded using the guide. The next discussions explain exceptions.

Soundex Coding Guide

After retaining the first letter of the surname and disregarding the next
letters if they are A, E, I, O, U, W, Y, and H, then:

     The number               Represents the letters
          1                    B, P, F, V     
          2                    C, S, K, G, J, Q, X, Z     
          3                    D, T     
          4                    L     
          5                    M, N     
          6                    R

Special Considerations


If the surname has a prefix, such as D’, De, dela, Di, du, Le, van, or Von, code it both with and without the prefix because it might be listed under either code. The surname vanDevanter, for example, could be V-531 or D-153. Mc and Mac are not considered to be prefixes and should be coded like other surnames.

Double Letters

If the surname has any double letters, they should be treated as one letter. Thus, in the surname Lloyd, the second L should be crossed out. In the surname Gutierrez, the second R should be disregarded.

Side-by-Side Letters

A surname may have different side-by-side letters that receive the same number on the Soundex coding guide. For example, the c, k, and s in Jackson all receive a number 2 code. These letters with the same code should be treated as only one letter. In the name Jackson, the k and s should be disregarded. This rule also applies to the first letter of a surname, even though it is not coded. For example, Pf in Pfister would receive a number 1 code for both the P and f. Thus in this name the letter f should be crossed out, and the code is P-236.

American Indian and Asian Names

A phonetically spelled American Indian or Asian name was sometimes coded as if it were one continuous name. If a distinguishable surname was given, the name may have been coded in the normal manner. For example, Dances with Wolves might have been coded as Dances (D-522) or as Wolves (W-412), or the name Shinka-Wa-Sa may have been coded as Shinka (S-520) or Sa (S-000). In other cases, first names were recorded as surnames.

If Soundex cards do not yield expected results, researchers should consider other surname spellings or variations on coding names.

Religious Figures

Nuns or other female religious figures with names such as Sister Veronica may have been members of households or heads of households or institutions where a child or children age 10 or under resided. Because many of these religious figures do not use a surname, the Soundexes for the post-1880 censuses frequently use the code S-236, for Sister. Similarly, some priests or monks may have been coded as B-636 (for “Brother”) or F-360 (for “Father”).

Single-Term Names

In 1880 many individuals, especially in Alaska or areas with many Native Americans, may have used only a single-term name such as Loksi or Hiawatha. Perhaps not until the 1900s did their descendants use a surname. Some researchers, therefore, may need to code a single-term name as though it was a surname.

H and W Rule

The letters H and W do not act as separators between letters having the same code value. As a result, such letters are treated as adjacent and are condensed into a single code. For example, the letter sequence “CHS” would be coded as 2, whereas without this rule, it would be coded as 22. Note that this rule has often been omitted in descriptions of Soundex.

Examples of Soundex Coding

     Name                Letters Coded       Coding
     Allricht            l, r, c             A-462
     Eberhard            b, r, r             E-166
     Engebrethson        n, g, b             E-521
     Heimbach            m, b, c             H-512
     Hanselmann          n, s, l             H-524
     Henzelmann          n, z, l             H-524
     Hildebrand          l, d, b             H-431
     Kavanagh            v, n, g             K-152
     Lind, Van           n, d                L-530
     Lukaschowsky        k, s, s             L-222
     McDonnell           c, d, n             M-235
     McGee               c                   M-200
     O'Brien             b, r, n             O-165
     Opnian              p, n, n             O-155
     Oppenheimer         p, n, m             O-155
     Swhgler             s, l, r             S-460
     Riedemanas          d, m, n             R-355
     Zita                t                   Z-300
     Zitzmeinn           t, z, m             Z-325

Further Information

If you would like to know more about Soundex, check out The Complete Soundex Guide, by Willis I. Else.