If an exact date is not known, then whenever possible estimate the dates rather than leaving them entirely blank. In this section, we discuss a few of the many ways in which this can be accomplished.
By Date of Will
If John Morgan made his will on 17 April 1853, and on 15 July 1853 the will was presented in court for probate, you know that John Morgan died between 17 April 1853 and 15 July 1853. It's best not to show “died 1853,” but specifically that he “died between 17 April 1853 (date of will) and 15 July 1853 (date will proved).” Be as precise as you can in presenting the information if you have the records to do so. It will prevent confusion when someone finds an entry that John Morgan sold a piece of land on 12 February 1853. If you had only entered the date as “ca. 1853” (about 1853) they might have been puzzled, but if you entered the death as being between the date of the will and the date it was proved (as above noted), those using your records will realize that he was living until at least 17 April.
Rule of Thumb
Studies of countless families living in the seventeenth and eighteenth centuries (and earlier) have determined that a good rule of thumb is that children were born two years apart. When you examine the lists of children of your earlier relatives, you may find gaps, but often that can be accounted for because of the death of a child. You know that the couple married in 1816, their first child Amy was born in 1818, Timothy was born in 1822, and Jonathan, the youngest, was born in 1824. When you discover a child Joseph, you can estimate that he may have been born ca. 1820. Do not state it as absolute fact, but include “ca.” (circa, about) to indicate that it is an approximated date.
You not only used the rule of thumb in the example given, but combined that with the fact that Jonathan was the youngest, and the couple married in 1816. It is often possible to glean clues on the approximate date from several related records.
Similarly, if you know the marriage date and don't have the birth dates of any of the children, you can approximate their births based on the marriage date. If John Taylor was married in 1838, and had three sons and a younger daughter, you can estimate that the sons were born ca. 1840, 1842, 1844, and the daughter ca. 1846, two years apart.
You can also use several census records to provide an approximated date. If the age of John is 15 in the 1850 census, 22 in the 1860 census, and 37 in the 1870 census, you can approximate that he was born ca. 1833-1838.
Choosing Their Own Guardian
Minors had guardians appointed by the court if they had any property due to them. Most states allowed those minors, upon reaching the age of 14, to choose their own guardians. If your ancestor is noted in court records as making that choice, you can estimate that he or she was between the age of 14 and 21. (By the latter age, a guardian would not be necessary if the person was deemed competent.)
As you progress in your genealogical pursuits, you will turn to the laws to determine the legal age for certain matters, to best evaluate the ages involved. Remember that states differed and laws changed.
Of Age to Marry?
You will find records of those who misrepresented age to get a marriage license; nonetheless, the marriage license can be a gauge for determining age. If the couple applied for the license without the consent of a parent or guardian, assume that they were of age unless other records prove otherwise. The legal age varied by location and time period, but usually the groom had to be 21 and the bride, 18. (The legal age was lower in some areas, especially for the bride.)
Why Bother with Approximate Dates?
The purpose of establishing an approximate date rather than leaving it blank is to better determine the records that can be examined. If you know only that your ancestor William Carr was born in Tennessee, then you have nothing on which to determine a course of action. If you know that he was born ca. 1791 in Tennessee, you see that by age he could have served in the War of 1812 and you can investigate the possibility of military service. Or, knowing he was born ca. 1791, you can examine the 1820 census of Tennessee to see if he was listed as head of a household, because he was about 29 at the time of that census. Other ideas will come to you, too, after that date is estimated.