3 generations on couch looking at tablet

A household is defined by the U.S. Census Bureau as all the people who occupy a single housing unit, regardless of their relationship to one another.

One person in each household is designated as the householder—the person, or one of the people ages 15 or older, in whose name the housing unit is owned, being bought, or rented. The relationships of all other household members are defined only in relation to the householder and then used to group households into different types. The two primary types are family households and nonfamily households.

Family households have a householder and one or more additional people who are related to the householder by marriage, birth, or adoption. Any children under age 18 who are the biological, adopted, or stepchildren of the householder are classified as “own children.” Family households include married couples with and without children under age 18, single-parent households with children, and other groupings of related adults such as two siblings sharing a housing unit or a married couple whose adult child has moved back home. Family households can also include additional people who are not related to the householder, such as a boarder.

Nonfamily households have a householder who lives alone or who shares the housing unit only with nonrelatives, such as roommates or an unmarried partner. Unmarried partner households can be either family or nonfamily households depending on which partner is designated as the householder and whether any additional household members are related to the householder. If an unmarried couple has a biological child together, then their household would be considered a single-parent family even though such a child would actually be living with both biological parents. However, if a child is related to only one partner of an unmarried couple, then the household can be either a single parent family or a nonfamily household depending on which partner is arbitrarily designated as the householder.

Census Relationship Categories Have Changed Over Time

Although the decennial census has always defined household types based on the relationships of household members to the householder, the number of possible relationships has expanded over time. In 1960 and 1970, respondents were asked to identify the “Head of the Household,” and in married couple households, only the husband could be designated as the “Head.” Response categories included “Wife of Head,” but not “Husband of Head.” Beginning in 1980, the term “Head of the Household” was replaced with “Person 1,” defined as the household member or one of the members in whose name the home is owned or rented. Response categories were also changed to include “Husband or Wife of Person 1”.1

With the rise in cohabitation in the 1980s, the 1990 Census was the first to include “Unmarried Partner” as a possible relationship to Person 1, in addition to “Housemate, roommate”. The 1990 form also added foster child to the “Roomer, boarder” category, and included “Grandchild” as a separate relationship type for the fi rst time. The 2000 Census listed “Foster child” as a separate relationship type, and although this category was excluded from the 2010 Census, it will be available again in the 2020 Census.

With the legalization of same-sex marriage by the U.S. Supreme Court in 2015, the 2020 Census will include “Same-sex husband/wife/spouse” and “Same-sex unmarried partner” relationship categories for the first time.2Separate categories will also be provided for “Opposite-sex husband/wife/spouse” and “Opposite-sex unmarried partner.” No changes will be made that would help clarify or consistently classify the appropriate household type for unmarried partners with children.

This article is excerpted from Mark Mather et al., “What the 2020 Census Will Tell Us About a Changing America,” Population Bulletin 74, no. 1 (2019).


1 U.S. Census Bureau, Decennial Census Questionnaires and Instructions, www.census.gov/programs-surveys/decennial-census/technical-documentation/questionnaires.html.

2 U.S. Census Bureau, Questions Planned for the 2020 Census and American Community Survey (Washington, D.C.: U.S. Census Bureau, 2018).