Geographic Information Systems store spatial data in computer layers that can be overlaid, queried and analysed, with the first true GIS developed by Roger Tomlinson for the Canada Land Inventory in the 1960s and parallel work at Harvard and in US agencies. A digital cadastre records land parcels, boundaries and ownership in the same machine-readable form. Together they let planners model land use, infrastructure and demographics quantitatively rather than by hand-drawn maps.
GIS transformed how cities are mapped, modelled and managed, making spatial analysis routine in planning, utilities and administration. The digital cadastre underpins property taxation, land markets and the data infrastructure of the contemporary city.