MHT Geographic Information System (GIS)

The Maryland Historical Trust has been developing GIS data on historic properties since 1991.  The primary system data consist of the National Register of Historic Places, state inventories of historic properties and archeological sites, the statewide record of archeological survey coverage, and MHT Historic Preservation Easement holdings.  The Maryland Historical Trust also develops and maintains the Maryland Heritage Area boundary files.

The system is being designed to facilitate Trust staff responsibilities in the areas of research, review and compliance.  Currently, the information is available to researchers at workstations in the library, and GIS data is distributed on disk to consultants, government agencies, and non-profit organizations for planning and research purposes.

Data Products

GIS data are available to outside users for research and planning purposes, provided in shapefile format.  Use the license agreement/order form to order data.

There are three historic sites GIS data sets commonly distributed:

National Register of Historic Properties

This data layer depicts boundaries of historic properties in Maryland that are listed on the National Register of Historic Places, a listing maintained by the US Department of Interior.

Maryland Historical Trust Historic Preservation Easements

This data layer depicts properties where owners have entered into an easement agreement with the Maryland Historical Trust to protect the historic character of the property.

Maryland Inventory of Historic Properties

This data layer depicts all historic properties which have been listed on the state inventory as having historic significance or potential historic significance. 

Each set consists of a digital file of the property locations and a database table which contains identification and attribute information.  See order form for pricing.

In addition, the USGS 7.5’ topographic quadrangles covering the State of Maryland are available as TIFF images.  The images are scanned at 250 dpi and are 256-color. See order form for pricing.

For additional information on ordering GIS data, please contact Gregory Brown at 410-514-7660.

On-Line GIS Data

Some of the data generated by MHT is available online through the Maryland Department of Natural Resources’ website, MERLIN Online.  Information found on MERLIN includes National Register properties, inventories of historic structures and districts, and easements held on historic properties. 

(The MERLIN link below will open in a new browser window, and loading takes some time; please be patient). 


For questions specific to historic resources information posted on MERLIN, please contact Gregory Brown at 410-514-7660.