By Reina Chano Murray

Historic preservation deals intrinsically with place: each of the historic resources we love can be marked to a location on our planet. As preservationists, we’re often concerned with 1) knowing exactly where these resources exist, and 2) not only preserving but understanding how they interact with or may be affected by their surroundings. This makes geographic information systems (GIS) a great resource for our field, since it allows us to create, manage, visualize, and analyze spatial data.

The National Trust’s foray into GIS began when its research division, the Preservation Green Lab (PGL), began working to make the case that older buildings contribute in significant, quantifiable ways to our lives. That successful effort resulted in the 2014 publication Older, Smaller, Better, which used big data and spatial analytics to find statistically significant links between blocks of older, smaller, mixed-age buildings, and various economic, social and demographic indicators. Since the 2014 study, the National Trust has worked to enhance the scope of its GIS work.

As the National Trust’s GIS project manager, my job is to provide GIS-related technical assistance to projects and demonstrate the applicability of GIS to historic preservation. We are also working to provide more GIS-related resources to the wider preservation community while creating best practices for working with GIS data in preservation.

A few examples of how we’ve used GIS recently to inform the preservation work of the National Trust and our partners:

Viewshed Renderings for Charleston, SC Harbor

A new terminal is being considered in Charleston, SC, which has the potential to significantly increase both the number and the size of cruise ships coming through Charleston’s harbor. I was asked to find a way to visually communicate the potential impact larger cruise ships would have on the historically significant viewsheds of Charleston’s historic district.

We used a combination of open source and proprietary GIS software (including SketchUp, Google Earth Pro, LASTools, and ArcGIS Desktop) to create a video that takes the viewer around to various vantage points in Charleston. In the video, superimposed 3D models of possible cruise ships in the harbor are shown, allowing us to visually demonstrate how these larger ships overshadow the height of the carefully preserved buildings in Charleston’s historic district. This video and the documentation it provided has resulted in the Army Corps of Engineers significantly increasing the area of potential effect (APE) of the new terminal, which affords us more opportunities to make sure the new terminal is developed responsibly in a way that limits its impact to this national historic landmark district.

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Atlas of Reurbanism

The Atlas of Reurbanism is PGL’s follow-up to Older, Smaller, Better. We’ve expanded on our initial analysis to offer baseline building and block information for 50 major cities across the country. We needed to create a methodology that would help us crunch a significant amount of data on this many cities in a timely fashion, and to create an interactive way for users to explore these datasets on their own.

Here too, we used a combination of open-source and proprietary GIS software such as PostgreSQL, PostGIS, ArcGIS for Server, and ArcGIS Online. In addition to a summary report released in November 2016, we are releasing city-specific fact sheets and web applications on a rolling basis.


In Progress

We have and will continue to add more examples of GIS-related work to our ArcGIS Online Organizational account, which you can check out at

Other things in the works include:

  • A partnership with University of Minnesota Media Lab and Esri (a leading GIS software provider) to put together a training platform called Earth Xplorers that teaches secondary school students about geography, GIS, and historic preservation.
  • Updated historic tax credit project maps for each state, congressional district, and certain cities to help advocates educate and lobby their representatives. These will  be completed in June.
  • Educational content in the form of webinars and blog posts to help historic preservationists to learn how to use GIS to not only analyze information and make informed decisions, but to also communicate widely about their work. The National Trust recently hosted our first GIS workshop on ArcGIS Online in February, and we are planning to release additional content over the coming months.
  • A tech track at our PastForward conference in November! Sign up for conference updates from the National Trust to get more details on this.

Reina Chano Murray is GIS project manager at the National Trust for Historic Preservation.


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.