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Person number of second mother (from programming)


00 = No second mother of this person in the household.


MOMLOC2 is a constructed variable that indicates whether the person has two mothers who live in the same household and, if so, gives the person number of the second mother (PERNUM). This variable is only non-zero when the parents identified for a child are both women. The method by which probable child-mother links are identified is described in MOM2RULE.

MOMLOC2 makes it easy for researchers to link the characteristics of children and their (probable) mothers.

If the person identified with MOMLOC2 has a spouse or partner identified through SPLOC, the spouse or partner will also be identified as a parent through MOMLOC. MOMRULE will communicate the method through which those relationships are identified.


Due to variation in the information available for linking mothers and children, there are some differences across years. For example, in 1968 and before, there is no "grandchild" value in RELATE. In these samples, "other relatives" who are under 22 are allowed to link to both "Other relatives" and to the "Child" of head as a mother when the age difference is appropriate. See the detailed notes on allowed links in MOM2RULE.

RELATE in years prior to 1997 referred to the relationship between a person and the family reference person, whereas after 1997 it referred to the relationship to the household reference person (with the relationship to the family reference person being indicated by FAMREL). For all years, MOMLOC2 is assigned within family (FAMNUMR), so the effect of the change in RELATE is minimized.

Comparability with IPUMS-USA

The development of new family interrelationship variables was prompted by the desire to have more comparability between different IPUMS projects and over time. The family interrelationship variables use common logic across different IPUMS projects. Each project has different allowed links because of different level of detail in each project, but the logic of assigning parents in ambiguous situations is the same.


  • 1963-2018: All persons.


  • 1963-2018


  • No weights are available for this variable. Please refer to MOMLOC2 for more information.