Historical Maps

Historical maps are cartographic documents created in past periods that capture boundaries, land use, infrastructure, toponyms, and cultural perspectives of their time. They are invaluable sources for reconstructing environmental change, property history, and urban development. However, they often contain distortions, inconsistent symbology, and biases that reflect their makers and methods. Digitizing and georeferencing historical maps allows comparison with modern datasets, enabling time lapse storytelling and rigorous spatial analysis of change across decades or centuries. Optical character recognition and machine learning can extract labels and symbology at scale, but human review remains essential. When digitizing, preserve the original sheet boundaries and marginalia because they provide context about survey conditions and intended audiences. Include citations that respect libraries and archives that steward these materials. Edge matching between adjacent sheets and reconciling inconsistent symbology are common tasks. Licensing terms often limit commercial reuse, so include rights statements. Recording the original map scale and publication context helps users judge what level of precision is reasonable.