Birth Information in U.S. Census Records

Did you know that the census can be a valuable resource in determining birth information about your ancestors?  See the summaries below for the details.  You may be surprised about what you can find out!

Birth Information in the 1850-1930 Censuses


  • 1850 – 1900 – Children under 1 year old are listed in fractions of twelve.
    • Example:  3 months old = 3/12
  • 1850-1930 – List age at last birthday before the census date.
    • May be an estimate
  • 1870 – 1880 – Enumerators were instructed to record the month of birth if a child was  born within the year.
  • 1900 – States a person’s birth month and year.
  • 1910 – Children not 2 years old are listed in complete years and months.
    • Example: 1 year 4 months = 1 4/12
  • 1920 & 1930 – Children not 5 are expressed in complete years and months .
    • Example: 3 years 2 months = 3 2/12

Birth Place

  • 1850-1930 – Indicate person’s U.S. state or foreign country of birth.
  • 1850 & 1860 – Some enumerators wrote the exact birthplace instead of U.S. state.
    • A list of these occurrences is in: Your Guide to the Federal Census by Kathleen W.  Hinckley.  GRO REF HA 37 .U6 H556 2002, p. 212.

Other Birth Information

  • 1890 – 1910– Mother of how many children and number of children still living .
    • Could lead you to birth, death, church records.
    • Could be a clue to previous marriages.

Birth Information in the 1790-1840 Censuses

  •  1790 – Lists number of free white males in age categories.
  • 1800-1810 – Lists number of free white males and females in age categories.
  • 1820-1840 – Lists in age categories, number of: free white males and females, enslaved males and females, free ‘colored’ males and females (“colored” most likely denotes African Americans, but those of other ethnic groups with a darker skin tone may also be included in this category.)

To see a list of census resources available in the Grosvenor Room, click the following link: Grosvenor Room Census Guides.


Dollarhide, William. The Census Book: A Genealogist’s Guide to Federal Census Facts, Schedules and Indexes. Bountiful, Utah: HeritageQuest, 1999. GRO REF HA 214 .D63 1999

Hinckley, Kathleen W. Your Guide to the Federal Census. Cincinnati: Betterway Books, 2002.  GRO REF HA 37 .U6 H556 2002

Minnesota Population Center. Enumerator Instructions. In Integrated Public Use Microdata Series: Census Microdata for Social and Economic Research. .

The National Archives.  Clues in Census Records, 1850-1930 and Clues in Census Records, 1790-1840. In Census Records. .

U.S. Department of Commerce. Measuring America: The Decennial Censuses From 1790 to 2000.  United States: U.S. Department of Commerce, 2002.

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