Thursday, April 30, 2009

Addresses Per Quadrant

Image: Distribution of Addresses by Quadrant

The four quadrants in Washington have large difference in terms of land area and population. Similarly, there are also large difference in terms of the number of addresses.

The Master Address Repository (MAR) has a total of 140,245 addresses:
  • NW: 64,825
  • NE 39,689
  • SE: 30,705
  • SW: 5,025

Tuesday, April 28, 2009

Field Research Today

Today, the MAR Data Team went to do field research. Sometimes information regarding an address needs to be gathered in the field as well as in the office environment. Each week or so we go out to the field.

Can anyone figure out where this picture was taken?

Monday, April 27, 2009

Collecting Data: Site Plans

Site Plan for part of Capitol Gateway Development

One of the strengths of the addresses in the MAR is that there are so many sources for the addresses. The above picture shows a site plan for Capitol Gateway Development. This picture was taken in December 2006. Capitol Gateway is located at the very eastern corner of Washington, DC.

Wednesday, April 22, 2009

416 Cedar Street NW = Address Anomaly

The address of the Takoma Park Library is 416 Cedar Street NW which is an address anomaly. Address anomalies are illogical addresses.

Why is 416 Cedar Street NW an address anomaly?

Cedar Street is an east west street and is numbered as such. The address 416 Cedar Street NW is in the NW quadrant and thus as one heads further west along east west streets the address numbers increase. As one heads west from 5th Street (in the NW quadrant) the number should be 500 or greater. Since 416 Cedar Street NW is located just west of 5th Street NW it should have a 500 block designation. A logical address for the Takoma Library is 500 Cedar Street NW. The library should change their address so it easier to locate.

Map of 416 Cedar Street NW. Click on image for larger view.

There are dozens of addresses that are illogical. These addresses are illogical because they do not follow the normal rules of Washington, DC's addressing grid system. These illogical addresses are also referred to as address anomalies. DC GIS maintains an address anomalies list which can be viewed and downloaded on the following webpage:

There are dozens of address anomalies in Washington, DC. DC GIS has spent hundreds of hours tracking down these cases and ensuring that the database matches the reality on the street.

Please check out our Address Anomalies Report (very large pdf).

Monday, April 20, 2009

What is the relationship between an address and an SSL (property record)?

It is a many to many relationship. One SSL (Square, Suffix, Lot) can have multiple addresses located on it. This often includes garden style apartment complexes as well as corner addresses with separate addresses facing each adjacent street. One address can also sit upon multiple properties. One single family residence can sit upon multiple lots. The address records only contain one 'base' SSL (usually comes from OwnerPly). The cross reference table contains the many to many relationship between Address ID and SSL. Some addresses do not have an associated SSL (such as metro entrances or many addresses on Federal property). In, the address table, each address record will only be associated with one SSL. That SSL will be the base SSL, which is the SSL under which the building rests upon. [Taken from the MAR FAQ (pdf)]

Monday, April 13, 2009

Henson Ridge Development

Click on image for larger picture.

Tuesday, April 7, 2009

The MAR Within DC Government

The MAR (Master Address Repository) was initiated, built and is maintained by DC GIS. DC GIS is the Washington, DC's Geographic Information System (GIS) Group which is part of the Office of the Chief Technology Officer (OCTO).

The Department of Consumer and Regulatory Affairs (DCRA) is the agency responsible for issuing new addresses. Applications for new addresses should be filed with DCRA. DC GIS assists DCRA in reviewing these address applications. Most of these addresses from the address application are then added to the MAR.

Monday, April 6, 2009

Vacant Lots & Addresses

Despite what many see as a crowded city, there are indeed thousands of vacant property lots in Washington. They are spread throughout the city but are especially prevalent in the lower income and more historic neighborhoods. In general vacant lots will not have an address in the Master Address Repository (MAR), unless:
  • A building with an address recently existed there. Example: 113 58TH STREET NE. (the address will have the STATUS of 'RETIRE').
  • A building will be built on this vacant lot in the near future. Example: 443 Woodcrest Drive SE.

The Integrated Tax System (ITS) does have addresses for many vacant lots in the city such as 1329 North Capitol Street NE.

Thursday, April 2, 2009

Blog Introduction

Is 441 4th Street NW a legitimate address? Where is the intersection of Naylor Road SE and R Street SE? What is an address anomaly? How many primary address are in Washington, DC?

This blog will deal with these types of questions. Washington, DC has a comprehensive Master Address Repository (MAR) which not only contains addresses but also contains:
  • Intersections
  • Blocks
  • Places Names (alias names)
  • Residential Units

In the coming months this blog will provide insights into Washington DC's Master Address Repository (MAR). Check out the official MAR Website.

We look forward to hearing feedback from the readers of this blogs.

Wednesday, April 1, 2009

Monthly MAR Data & Information Report: March 2009

Dataset Numbers:

  • Addresses: 141,633
  • Residential Units: 180,060
  • Aliases: 5,105
  • Street Name Alias: 1021
  • Intersections: 16.359
  • Block: 15,826
  • Address / SSL Cross Reference Table: 235,493


  • Major update of addresses at the large Capitol Quarter development which is located just south of the Southeast Freeway between 3rd & 5th Street SE. See:

  • A major update of addresses at Emerson Park townhouse development which is located just south of the Fort Totten Metro Station.

  • Fixed incorrect Zipcode values for addresses on a part of Bolling Air Force Base.

  • National GRID issues were fixed

Residential Units

  • Significant progress was made in March on improving the data in the Residential Units Table. Despite the progress there most probably between 10,000 - 15,000 missing residential units (estimated). It is estimated that the residential unit data is about 87% - 94% complete.


  • Old blocks which no longer exist were deleted. 107 new blocks were added. These new blocks were often located in new residential developments such as Phillips Park and Emerson Park.


  • A few street centerline updates were emailed to the folks at DDOT and OUC.

  • Automated the updating of National GRID Coordinates values when addresses are loaded using the MAR Batch Data Loading Procedure.
  • An update to Address / SSL Cross Reference Table so that when new addresses (except those that are retired) are added, the address and its associated SSL value is automatically populated into the Address / SSL Cross Reference Table.