A soundex code is a four character representation based on the way a name sounds rather than the way it is spelled. Theoretically, using this system, one should be able to index a name so that it can be found regardless of its spelling. The Soundex Coding system was used by the National Archives to index census and immigration records. In the 1930s, the WPA used this system to index the 1880, 1900, 1910, and 1920 federal censuses on 3x5 cards. Microfilms of these indexes are available at many libraries and archives.
- Soundex codes begin with the first letter of the surname followed by a three-digit code that represents the first three remaining consonants. Zeros will be added to names that do not have enough letters to be coded.
- Soundex Coding Guide (Consonants that sound alike have the same code)
1 - B,P,F,V
2 - C,S,G,J,K,Q,X,Z
3 - D,T
4 - L
5 - M,N
6 - R
The letters A,E,I,O,U,Y,H, and W are not coded.
Names with adjacent letters having the same equivalent number are coded as one letter with a single number.
Surname prefixes such as La, De and Van are generally not used in the soundex. Mc, Mac and O generally are not considered prefixes for soundex.