Follow Census Clues to New Records
Census enumerations are packed with details, both large and small. Once you get past the names, ages, and relationships of the listed individuals, there are still many other clues to be found hidden among the census columns. Everything from the street address to the age of a mother at the time of her first marriage may hold a clue that leads to new records. Generally, you should look at every single piece of information contained in a census record (or any record for that matter) and ask yourself what it tells you about your ancestor. Does it fit what you know about him or her? If there is an anomaly, follow it up. It may be an error introduced during the census enumeration process, or it may just be the key to learning something new.
Many, many clues can be gleaned from a census record if you take enough time to fully explore the data recorded in each column, and compare the answers from one census to the next. To get you started, here are a few of the more obvious items to investigate in U.S. federal census records.
Number of Children
Column 11 of the 1900 census and Column 11 of the 1910 census asked for “mother of how many children.” When combined with the “number of children living” indicated in the next column, much can be learned. First compare the number of living children with the number of children listed in the household. Do they match up? If not, this may indicate children who were old enough to move out on their own (married or not), or were living elsewhere, such as in an institution, as an apprentice to another family, or with relatives. If there are more children listed in the household than born to the mother, this could possibly indicate a prior marriage of the father. Go back to previous census years to see if you can identify these children and then search for them again in 1900 or 1910 to learn where they are living.
A discrepancy between the number of children born and the number still living obviously indicates that one or more children have probably died. Again, go back to prior census years to identify as many children as possible and, hopefully, determine which ones are deceased prior to 1900 or 1910. Follow up with a search for death certificates, obituaries, and so on.
Marriage Age and Year
The 1910 and 1920 U.S. federal census both contain a column for “number of years in present marriage.” Some simple subtraction gives you an approximate date of marriage — something easy to follow up in marriage records.
U.S. federal census records from 1790 through 1840 include only the name of each head of household, with statistical columns to group other household members by gender and age. At first glance this may seem fairly useless information, but by following patterns of age and gender groups in each household through successive census years, you can generally glean more from these early census records than you might think. Learn more in my article “Digging Details from Pre-1850 U.S. Census” (
For ancestors who lived in 1930, pay special attention to Column 15, which asks for “age at first marriage.” For married couples, compare that age with their “age at last birthday” from Column 13 to determine the approximate year that each was married. In many cases it will be the same give or take a year or two, as you might expect for a married couple. But if this subtraction indicates that the husband was first married eighteen years ago and the wife only eight years ago, there is likely at least one other marriage in the picture. On the other hand, it could just be a recording error on the part of the census enumerator.
Year of Immigration and Naturalization
The 1900, 1910, 1920, and 1930 censuses each include a column that asked for the individual's year of immigration, which can obviously help narrow the time frame for passenger arrival manifests. It's not uncommon to find a wife immigrating a few years after her husband, as he came ahead to pave the way for his family. In the case of married couples, compare the year of immigration for both spouses with the date of marriage (actual or approximate) to learn if the couple was likely married before or after their arrival in the United States, which in turn narrows the search grid for the wife's parents.
The 1910 census includes a column (30) to record whether the person was a “survivor of the Union or Confederate Army or Navy,” indicated by “UA” for Union Army, “UN” for Union Navy, “CA” for Confederate Army, and “CN” for Confederate Navy. The 1930 census (Column 31) also asks about military service. A “CW” in this column indicates a Civil War veteran, “Sp” for Spanish-American War, “Phil” for Philippine Insurrection, “Box” for Boxer Rebellion, “Mex” for Mexican Expedition, and “WW” for World War I. Follow up these individuals in military service and pension records.
Running vertically down the left-hand side of the 1880 and 1900 through 1930 censuses, you may find a street name indicated. This will vary depending on whether your ancestor lived in a city/town, or a more rural area. Sometimes streets were just not recorded. If they were, however, the first column to the right of the street name includes the house number. With this information you can locate your ancestor in city directories or place their house on a historical or present-day map. The map can be used to place their neighbors as well, including those who lived behind them or across the street, as well as next door.