By Dan Watts

Geographic information systems (GIS) are an invaluable part of the practice of historic preservation. By harnessing the power of geospatial data, preservationists, planners, and community members can more effectively manage change, protect historic resources, and engage the public in efforts to create better communities.

GIS has long been a part of preservation planning and has been used extensively on everything from building surveys and inventories to the cataloging of architectural styles or building materials. But because of cost, use was traditionally limited to governments or organizations with budgets large enough to purchase the necessary licenses and hardware. As a result, the full analytical power of GIS was often experienced only by a small group of experts, while the public saw static end results such as printed maps.

However, the last several years have produced a wealth of easily available open-source and technically robust GIS platforms that have transformed the ways in which the public experiences and interacts with GIS technology. If I had to pick one word to describe the transformation, it would be accessibility. This revolution in accessibility is probably best embodied in the potential of web GIS. Simply defined, web GIS is a combination of internet and GIS technology made widely accessible through a web browser interface.

Web GIS has vastly democratized access to GIS’s analytical power from virtually anywhere and with little or no cost to end users through web mapping applications. These applications often have the capability to make available many of the same analytical tools as desktop GIS, enabling users to examine data in new ways.

In 2016, the Washington DC Office of Planning released an interactive web application, HistoryQuest DC, which provides information on more than 120,000 buildings within the District of Columbia. The information is presented in an easily understood format and the application also contains analytical tools that enable users to query or sort the data behind scenes. Consider the alternative of sifting through a 120,000+ record database!

HistoryQuest DC, courtesy of the Washington DC Office of Planning

At the same time, web mapping applications are also challenging the traditional ways in which data is displayed and interacted with. In early 2017, the New York City Landmarks Preservation Commission launched a 3D web mapping application as part of a public outreach effort following the designation of a new historic district in upper Manhattan. The application allows users to freely navigate the 3D environment of the Morningside Heights neighborhood and in doing so gain a more complete and nuanced understanding of the buildings that make up the historic district and the context in which it’s located.

Morningside Heights Historic District Explorer, courtesy of the NYC Landmarks Preservation Commission

I believe that, in many ways, we’re seeing the future of GIS unfolding in front of us. The democratization of geospatial technology almost certainly means that the future of GIS in preservation planning will be one of greater access to information as well as increasing access to tools, especially those that are open-source. This will enable an ever-larger group of people to work with data in the geospatial environment. The case studies referenced above are only the tip of the iceberg in terms of how GIS accessibility will affect preservation planning and I look forward to innovations to come.

Dan Watts is a preservationist and data aficionado and works as a GIS Administrator at the New York City Landmarks Preservation Commission.

About this series

Follow along this month as we learn how others are using data to support, improve, and create good preservation practices. The Action Agenda prioritizes data collection and analysis to support key efforts of legacy city preservation:

Action Item 3: Use data to support and improve good practices.

Preservationists need data that goes beyond the facts of buildings, styles, and architects. Good data and layered multidisciplinary analysis can inform strategic decision-making on the ground, prioritize limited funds, support coalition-building with organizations in allied fields, direct preservationists in refining practices and tools in challenging legacy city contexts, and shape effective advocacy efforts. In particular, rigorous analysis should examine how reinvesting in older and historic buildings and neighborhoods compares to demolition with regard to social, economic, and environmental outcomes such as community stability, foreclosures, and property values.