Howard County Import

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This is the second draft...


This is a project to import public domain data from Howard County (Maryland) GIS division.


Interested OpenStreetMap editors are welcome to join our import. These users are working primarily on this project:


Here is a short list of the intended results for the map

  • Import the building footprints county-wide
  • Import the address points and blend with the buildings where there is a one to one correspondence.
  • Review street centerlines for missing streets and street names.
  • Review other layers of interest including, schools, fire stations, parks, cemeteries, food establishments, farms, golf courses, libraries, liquor licenses, etc.


  • Community involvement
  • Accuracy
  • Documentation
  • Respect existing edits
    • There may be data that represents real world changes since this GIS data was published.
  • Attribution
    • Though in the public domain, we should still reference the creator.


All data being imported is coming from Howard County open data portal:

Data source site:

Type of license: Public Domain, and written confirmation (

ODbL Compliance verified: Yes


This project started in September 2016, with analysis and coding. Import is expected to begin by late 2016.

Test Area

Buildings in Howard County inside Eldridge postal code 21075.


QGIS will be used on the county shapefiles to de-project, as well as mix case and normalize the street names. Then buildings which contain only one point address were merged, and joined via unique IDs to remove those address points that are now duplicated. Currently, this process is being done by hand, but a Python script may be developed. A script was written to then take the resulting shapefiles (buildings and address points) and create an OSM (XML) file, which JOSM can load.

The actual import will be done in JOSM, partitioned by ZIP code boundaries. JOSM Validation will be used to check for automated errors. Additional error checking will be performed using OSM Inspector with Address and Geometry tabs.

Tagging Plans

building = yes (default or house when in large residential areas)

addr:housenumber = <Number>

addr:street = <Unabbreviated Mixed-Case Street Name>

addr:city = <City>

addr:postal = <ZIP Code>