About the California Cultural Resrouces Map
This webmap of National Register of Historic Places (NRHP)listed properties in California was manually drawn using original NRHP nomination forms. All NRHP listed buildings, districts, and structures are drawn as shapes that reflect the real boundaries of the resources as accurately as was practical. In many cases, single, listed buildings are represented by the boundaries of the tax parcels they occupy. Parcel shapes were copied from county assessor GIS data when possible.
2,880 properties have been listed on the NRHP in California since the program was created in 1966. However, only 2,587 resources appear on this webmap. 217 sites were omitted because they are archeological sites. They are sensitive to looting and vandalism and their locations are confidential. 43 resources are known to have been destroyed. Resources like buildings that have been demolished are not automatically removed from the National Register. 14 boats and an operating train that have moved since their listing were excluded as well. The balance of properties that were not mapped were omitted because they were duplicative listings like boundary increases or they were very recent listings.
The possibility of doing quantitative studies with cultural resources GIS data has intrigued me for a few years now. There are all sorts of issues that arise with this topic though. Cultural resources are fundamentally qualitative in nature which makes any kind of quantitative process iffy. We also don’t have very good foundational systems in the US for this kind of analysis. Inventories or census like surveys are, in my opinion, a first and necessary step towards quantitative analysis of pretty much anything. The best inventory we have for material cultural resources in the United States is the National Register of Historic Places (NRHP). Some states have local, more comprehensive, inventories of resources. The NRHP is mostly an inventory of material culture although Traditional Cultural Properties and Landscapes are being listed more frequently in recent years. The NRHP has a number of problems that make it difficult to work with though. The NRHP has no scale: something is either listed or not. The British system, for example, has three grades of importance. The NRHP is a biased selection. Properties are nominated via a process that requires rigorous documentation and research by the nominating party. This process often requires the services of a professional historian consultant. Without active sponsorship, properties remain unlisted. Properties listed on the NRHP are not monitored in any consistent way after listing. This leads to situations where properties continue to be listed long after they are demolished or destroyed. Another issue with the NRHP are the criteria used to determine cultural significance and the way it is applied. The NRHP criteria are culturally biased and are used to judge resources by biased evaluators. It is hard to imagine escaping the subjective and qualitative nature of determining what is or isn’t culturally important though. The NRHP at least has a documented set of criteria and lots of documentation on how to apply those criteria.
Another significant issue with the NRHP is that, as of summer 2020, there was no available, reliably accurate, spatial database of listed resources. The National Park Service does have GIS data available for download. But for the project I had in mind, what the NPS had was not accurate enough. California has a spatial cultural resource database but it resides in the California Historic Resources Inventory System (CHRIS) and is not available to the public for free. It is also not available as a state-wide, centralized, database. The direct inspiration for making this dataset were devastating wildfires of 2020 which destroyed 2 NRHP listed structures. Figuring out which properties were threatened by fire required a spatial dataset. The first project I used this data with was an attempt to gauge climate change related risk to listed resources which you can read about here: California NRHP Climate Risk Study
This webmap was made using the AGIS Javascript API.
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