Background: Organized by household, North American census data promoted research into household composition, but discouraged research into connections between urban households. Yet these constitute "communications communities" that powerfully influence demographic decisions (Szreter 1996).

Objective: How can we uncover relations between urban households? From spatial cues, can we infer social connections that generate constraints on or incentives for the formation of a household, its break-up, reconstitution, or relocation?

Methods: For Montreal and its suburbs, 1881‒1901, we employ double geocoding and lot-level precision to explore a dozen types of relationships. Samples for experiment are drawn from a local historical geographic information system (HGIS) that integrates tax roll and directory with census data.

Results: 'Family' was socially embedded at three levels. Neighbouring of kin was strategic, and kinship was a factor in employment, enterprise, and property development as well as residential choices. In managing property, family networks operated with a horizon of four generations.

Conclusions: Introduction of geographic coordinates offers a critical set of neglected cues to relationships between households, such as business partnerships, credit, or use of transit or telephone. In an urban HGIS, advantageous features are lot-level precision and facilities for coding and matching addresses to accommodate alternative levels of spatial aggregation.

Contribution: Geocoding is shown to be a breakthrough innovation for exploring urban connectivity. Experiments with maps and networks as tools of visual thinking invite us to rethink the ‘census family’ at higher levels of relatedness.