The District of Columbia

Zip Codes (ZipCodePly)

Zip Codes (ZipCodePly)

by US Postal Service on 03/26/2009

Keywords
About: boundaries, society, Postal Service, location, Zip Codes, Five Digit Zip Codes, Postal Service
Taking place at: Washington, D.C., District of Columbia, DC, DC GIS, DCGIS

Abstract

Zip Codes (5-digit). The dataset polygons represent location and attributes of zip codes, created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies.

Zip Codes were identified from public records (US Postal Service) and created selecting arcs from the street centerlines and vector property map.

All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters.

METADATA CONTENT IS IN PROCESS OF VALIDATION AND SUBJECT TO CHANGE.

Purpose

This data is used for the planning and management of Washington, D.C. by local government agencies.

Access constraints

Contact OCTO GIS. Any data obtained outside of OCTO GIS are unauthorized copies.

Use constraints

Acknowledgment of the DC Geographic Information Systems Program (DC GIS). The District of Columbia Government makes no claims as to the completeness, accuracy or content of any data contained hereon, and makes no representation of any kind, including, but not limited to, the warranty of the accuracy or fitness for a particular use, nor are any such warranties to be implied or inferred with respect to the information or data furnished herein.

Point of contact

GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: (202) 727-5660
hours: 8:30 am - 5:00 pm

Credits

US Postal Service

Data accuracy

Accuracy
Data believed to be complete and accurate as of the time period cited. Subject to change. Not validated by source and/or responsible agency.

Staff compared the MAR address point to the Zip Code polygons noting the following errors and discrepancies:

1) address points that do not fall in the correct zipcode
2) zipcode polygons that did not follow designated features, such as street centerlines, alleys, and vector property lot lines.

Staff also used the USPS website to research and verify zip codes by address. Topology was used to ensure no overlaps or gaps existed between zip codes. Staff ensured the new unique zip codes were correctly assigned and mapped.

Logical consistency
Not validated by source and/or responsible agency.

Completeness
Data believed to be complete and accurate, subject to change. Digital version compared with original source data for accuracy and completeness. In process of validation by source and/or responsible agency.

Horizontal positional accuracy
The snapbase and vector property map data was used to construct most of the zip codes. Planimetrics compose most of the snapbase. They were captured at a 1:1000 map scale accuracy (well defined points with .83 ft). Since the vector property map is best-fitted to the planimetrics, it is close but not as accurate as the planimetrics.

Vertical positional accuracy
N/A

Lineage / Sources

Lineage / Processes
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

phone: (202) 727-1761
fax: (202) 727-5660
hours: 8:30 am - 5:00 pm
Zip code lines were identified from existing shapefiles from Spatial Systems Associates. These were intersected with the SIS street center line, transferring attributes to individual arcs. Some arcs remained unattributed, since they crossed zip code boundaries. These arcs were hand attributed and verified from the published USPS zip code list. Polygons were then created from these lines.

Attribute data was provided by United States Postal Service publications and an additional URL from the EPA Enviromapper website.
GIS Data Coordinator
in Office of the Chief Technology Officer

441 4th st NW, Suite 930 South
Washington DC, 20001, USA

fax: 202-727-5660
hours: 8:30am - 5:30pm
The Address points from the Master Address Repository (MAR) were matched against the US Postal Service Address Information System (AIS) Zip+4 data product. The Zip+4 data contained 5 digit zip codes for known postal addresses in DC.

Staff developed a custom visual basic, ArcObjects program to assign the addresses in the MAR with the 5 digit Zip Code from AIS Zip+4 data, matching on address. The program successfully matched and assigned 91% of the addresses in the MAR.

Zip codes were originally created using centerlines. Using the MAR points with assigned zip codes, staff recreated and moved the zip code boundaries where zip codes occurred on both sides of the streets. The zipcode boundaries were snapped to the snapbase, alleyways, and vector property lot lines. New unique zip codes were added to the original zip code boundaries. PO box zip codes were created where the respective post office is located.

After QA/QC, staff updated zip code boundaries based on error resolution and research findings. Several new unique zip code polygons were created and deleted as well.
GIS Data Coordinator
in Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

fax: 202-727-5660
hours: 8:30am - 5:30pm
Medicaid recipient and uninsured population data was added from data provided by the DC Department of Mental Health.

in OCTO



Staff obtained a list of zip codes from the US Postal Services and updated the zip code layer. For unique zip codes, those assigned to buildings, agencies, etc, staff used the USPS website and web research to determine where the zip code was located. If the USPS website indicated that an address had a unique zip code as its primary zip code, the bulding polygon containing the address point was captured. If the unique zip code was not the primary zip code, a polygon was drawn inside the building polygon.

in OCTO



Merged zip codes 20336 and 20332 with 20032. Resolved topology errors.

Distribution

Contact OCTO GIS.

Distribution liability
Acknowledgment of the DC Geographic Information Systems Program (DC GIS). The District of Columbia Government makes no claims as to the completeness, accuracy or content of any data contained hereon, and makes no representation of any kind, including, but not limited to, the warranty of the accuracy or fitness for a particular use, nor are any such warranties to be implied or inferred with respect to the information or data furnished herein.

Distributed by
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

phone: (202) 727-1761
fax: (202) 727-5660
hours: 8:30 am - 5:00 pm

Entity

DCGIS.ZipCodePly

Attributes

  • TYPE
    Zip code type
  • Shape / ESRI
    Feature geometry.
  • ZIPCODE
    Zip Code value
  • GIS_ID
    OCTO GIS sequential identifier
  • OBJECTID / ESRI
    Internal feature number.
  • EPA_URL
    EPA web link url with zip code map
  • NAME
    Name of feature or agency the Zip Code represents.
  • SHAPE / ESRI
    Feature geometry.
  • MEDICAID_RECIPIENT
  • UNINSURED_POPULATION
  • WEB_URL
    Web Link URL
  • SHAPE.AREA
  • SHAPE.LEN

Metadata

FGDC Content Standards for Digital Geospatial Metadata / FGDC-STD-001-1998 as of 03/30/2009

Provided by
GIS Data Coordinator
in D.C. Office of the Chief Technology Officer

441 4th St NW, Suite 930 South
Washington DC, 20001, USA

phone: (202) 727-1761
fax: (202) 727-5660
hours: 8:30 am - 5:00 pm