Gabriel Ahlfeldt, lecturer at the London School of Economics, presents on the digital conversion of data derived from Olcott’s Blue Books, the unique dataset of historical land values, land uses, building heights, and other information in Chicago and its suburbs, published annually between 1900 and 1990. The digitization project, which opens up new possibilities for statistical analysis of long-run adjustments in land values, involves using geographic information system (GIS) software to create a rectangular grid following Chicago’s street pattern and produce a unique spatiotemporal dataset, providing insights into changes in the spatial structure of the city.