This project will: 1) develop the most ambitious H-GIS municipal boundary data in the world by recreating municipal boundaries for the whole of France year by year over the last two hundred years, linking historical administrative units to population and transport accessibility data. 2) Develop and use a multimodal model of transport networks to analyse changes in economic geography and historical demography over the period. 3) We will use this HGIS to analyse spatial and historical variations in population density and population geography as a proxy for economic development over the period. Linked to other rich historical data, this HGIS will become a reference for all social scientists. This important tool is still missing as previous attempts have not succeeded in producing a reliable and accurate database of boundary change, mainly because of the lack of a systematic collection of historical records to reconstruct past administrative units. This project combines the strength and expertise of French Institute for Demographic Studies (INED), the Cambridge Group for the History of Population and Social Structure (CAMPOP, Cambridge), and ThéMA Lab from Bourgogne-Franche-Comté University. It also counts with the implication of the National Institute of Geographic and Forest Information (IGN) and the active support of some of the most prominent European scholars in our Advisory Board. Thanks to a team of highly-qualified research associates and research assistants we can guarantee with confidence the success of this ambitious project. The unique combination of the historical and cartographic expertise of our teams will allow us to fill this major historical gap. Thanks to the seminal work by Séguy and Théré, who compiled a list of all boundary changes since 1801, we have devised a method to reconstruct historical administrative boundaries efficiently and accurately. We will be using a combination of historical and cartographic sources drawing upon administrative records, official maps from the Service Géographique de l’Armée (SGA) and IGN, and other cartographic material such as cadastral mapping, and recent land surveys. Overall c.15% of all communes, will require exhaustive archival research all over France in order to digitise contemporary maps of administrative boundaries. Over the years the CAMPOP has developed significant expertise by reconstructing English and Welsh parish-level boundaries for the period 1831-1881 with sources scarcer than in the French case. The project will draw upon the significant expertise of ThéMA in recreating historical transport infrastructure, to complete the French historical road network and all navigable waterways over three centuries. The preliminary work we have been carrying out since the submission of our first-round application has vindicated our initial estimates and confirmed the feasibility of the project under strict time and cost constraints. Our deliverables include: 1) the first and only set of GIS boundary data for all French communes from 1790 to the present linked to population data and transport networks. The novel methodology devised for this project will be replicable to other countries. 2) Linking large databases to fine spatial units through time will be a major breakthrough in the application of quantitative and comparative analyses of large datasets to history. 3) Build a truly multi-modal model of analysis to assess the effect of changing journey times and costs on spatial population dynamics and patterns of economic development. 4) All our data will be on open access to provide transparency, traceability and guarantee the dissemination of our work. The scientific legacy of our project is guaranteed by depositing all the data to the Archives Nationales. 5) Public impact and engagement with our work will be enhanced by the diffusion through popular platforms such as IGN Géoportail and Remonter le Temps portals, Cambridge’s Travel in Times’ and Geneanet’s websites.