What's the DC Master Address Repository?

The Master Address Repository (MAR) is a database of addresses, blocks, intersections, place names, and other location identifiers in the District of Columbia.

Each address in the MAR is standardized and assigned a unique Address Identification Number (AID), geographic coordinates, and other relevant information, including its Ward, ANC, Voting Precinct, and more.

It is mainly used by DC government employees, who want to compare and relate sometimes messy location data across databases and agencies. But the MAR can also be helpful to businesses, non-profits, and individual DC residents.

What's this Site?

This website lets you easily look up many locations in the MAR at once!

To use it, you will need a CSV (comma-separated values) format file on your computer that has:

You can include as many address rows as would like and, so long as you have at least one column with location information, your file can contain any number of other columns. It's also fine for your location column to include any combination of addresses, intersections, blocks, AIDs, and place names—feel free to mix it up!

Once that's in order, head to the DC MAR Tool site and:

  1. Find and select the CSV file from your computer;
  2. Choose a column that contains location identifiers;
  3. Click 'Go!' to run the tool. Any locations cannot be found in the MAR can be seen by clicking 'View Failures;'
  4. Download the results either in CSV or GeoJSON format, with all information from the MAR added in;
  5. Share the results as a map with someone else (if you would like) by clicking 'Create Gist' under 'Save the map.'


This tool was developed by Emanuel Feld.

Send questions, issues, ideas, feature requests, rants, or raves on Twitter or by email at evonfriedland at gmail dot com.