In most years the census taker asked individuals their age in terms of “age at last birthday” as of the Census Day. The person's age was written in whole years, except as noted in the last column of the table below. At no time has the exact day of birth ever been asked.

Except for the 1950 census (see “Note” in F. below), the census transcript shows complete years and months.

The transcript shows “0/12 months.” This indicates that the child was not yet one month old on the Census Day for that year's enumeration.

The transcript shows “1 3/12”, indicating that the child was one year and three months old on the Census Day.

A child enumerated in the 1920 census who was born on 10/20/18 would be shown on the transcript as “1 2/12.”

Since the census was rarely taken on Census Day, the census transcripts may not always reflect accurate information as of the Census Day. Exercise judgement when evaluating a census transcript which shows the age in months.

The following table shows the date of the Census Day for the period 1900 - 1970, and other data pertaining to each census.

In the following areas, the Census Day was not always the same as the Census Day for the rest of the U.S.