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Addressing and Property Standards

Location Identifiers

The Master Address Repository (MAR) provides District agencies with an authoritative single source for accurate location-identifying data within the District of Columbia – includes building addresses, blocks, street intersections and place names (points of interest). Each record contained in the MAR is linked to a specific geographic point and primary key identifier used across DC agency enterprise systems.
Agencies, and the public, are encouraged to adhere to the following minimum guidelines when creating or appending spatial data for mapping location identifiers in DC:
  • Geocoding, the process of assigning x,y (or lat/long) coordinates, should be performed using MAR Web Geocoder for individual spreadsheets and local databases. MAR web services for web apps and geoprocessing tools.
  • Primary Key fields should be kept in all location-identifying enterprise datasets for best integration across other District agency systems. The following are primary key fields are in MAR,
    • ADDRESS_ID: unique address identifier used in many point datasets (also seen as ADDRID)
    • UNIT_ID: unique identifier for the residential units layer
    • MARID: unique identifier used for intersections and blocks
    • SSL: known as Square Suffix Lot and is a unique identifier used in property datasets
  • Refrain from aggressive web scraping and adhere to Responsible uses of MAR Web Services for geocoding.

Find data for addressing on Open Data DC.

Property Lots

The District's Vector Property Mapping (VPM) project’s extensive data depicts active citywide lots with the ability to display history and change of property over time. City planners, business development leaders, private companies and residents are encouraged to use VPM when creating or appending data for lots in DC.

Find data for property lots on Open Data DC.