Genealogy Aids

Social Security Numbers
The prefixes indicate the state in which the Social Security Number was issued. This will assist you in identifying the state in which the individual lived or was possibly born. This is a big help when you’re searching the Internet.

The nine-digit SSN is composed of three parts:

    • The first set of three digits is called the Area Number
    • The second set of two digits is called the Group Number
    • The final set of four digits is the Serial Number

More Information:

    • The SSN Numbering Scheme
    • Social Security Online
    • Social Security Number Prefixes


When to use “cal”, “est”, “abt”, “bef”, “aft” in your research documents and/or Family Tree.

Use “cal” for calculated when you can actually calculate one date with information from another date. For example, with a death date and an age at death you can calculate a birthdate. “Cal” before the date is a warning sign add “age at death” in the “Source Comments” with an explanation of the possible difference in days.

Use “est” for an estimate when there is some basis to give a date.

Use “abt” for about (approximately) when you have a very general time period. You can also use “circa”.

Use “bef” for before when you have a date when the person was dead, such as the date a will was probated or proved but not the actual date of death. Use “bef” with the explanation in the “Source Comments”.
◦Do not assume that a marriage took place before the birth of the first child. There may have been an earlier marriage for one of the parents.
◦Do not assume that a daughter died before her father if she was not included in his will. She may have been given her inheritance when she married and so was not named in the will.
◦Wills are usually probated within a year after the death.

Use “aft” when there is firm evidence of a date when the person was known to be alive. For example, the date a wife is made the executor of her deceased husband’s will (1880) tells you that the wife died after 1880.

Notice that the margin of error increases from “calculated” to “estimated” to “about”. “before” and “after” can indicate a wider margin of error.