How did women contribute to the ‘industrial revolution’ in Montreal? With the help of an HGIS, can we uncover some roles whose importance we have failed to recognize? The reorganization of production that we still think of as the harnessing of the steam engine, entailed a continual repartitioning by gender, as well as rearrangement of spaces, concentrating workers in large factories, in cities of unprecedented size, and under wider and deeper structures of corporate management. Despite a generation of scholars more alert to the concerns and agency of women, flaws in the ‘comprehensive’ census make it difficult to get an adequate perspective on the restructuring of work. For more than two-thirds of Montreal women over age 15, the nominal census provides no information about their activities, earnings, or places of work. 1 To gain insight into their roles in the spectacular expansion of an urban economy, we must tap alternative sources, apply more supple concepts of work, and anchor workplaces – domestic and institutional as well as industrial and entrepreneurial – in the urban space. Several chapters of this volume point to the value of an HGIS in the analysis of sites of social change. Along these lines, I shall argue the potential of a well-conceived HGIS for integrating rich local sources as an ‘information system’. By coupling additional sources we uncover their complementarities and wring more out of the census itself.