| Census Tracts - 1940 - DC (Tract40Ply) | |
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Data format: SDE Feature Class File or table name: DCGIS.Tract40Ply Coordinate system: State Plane Coordinate System Theme keywords: society, Census Tracts, Tracts, boundaries, Government Jurisdictions, Census |
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Abstract:
Census Year 1940 Census Tracts. The dataset contains polygons representing CY 1940 census tracts, created as part of the D.C. Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies. Census tracts were identified from maps provided by the U.S. Census Bureau and the D.C. Office of Planning. The tract polygons were created by selecting street arcs from the WGIS planimetric street centerlines. Where necessary, polygons were also heads-up digitized from 1995/1999 orthophotographs.
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. |
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Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.
Census Year 1940 Census Tracts. The dataset contains polygons representing CY 1940 census tracts, created as part of the D.C. Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies. Census tracts were identified from maps provided by the U.S. Census Bureau and the D.C. Office of Planning. The tract polygons were created by selecting street arcs from the WGIS planimetric street centerlines. Where necessary, polygons were also heads-up digitized from 1995/1999 orthophotographs. 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.
This data is used for the planning and management of Washington, D.C. by local government agencies.
ground condition
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.
441 4th St NW, Suite 930 South
U.S. Census Bureau D.C. Office of Planning
Data believed to be complete and accurate as of the time period cited. Subject to change. Digital version compared with original source data for accuracy and completeness. In process of validation by source and/or responsible agency.
In process of validation by source and/or responsible agency.
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.
In process of validation by source and/or responsible agency.
N/A
boundaries and attributes
1940 Census tracts were identified from public records (U.S. Census Bureau and D.C. Office of Planning) and initially created by selecting street arcs from the WGIS planimetric street centerlines. Where necessary, tracts were also heads-up digitized from 1995 orthophotographs. The digitized arcs and polygons were converted to shapefiles. The census tract datasets were selected using the shapefile from the snapbase coverage, creating coincident geography with the other DC GIS datasets. Digitized lines lacking a corresponding planimetric feature were retained. Snapbase arc attributes were populated with appropriate census designations. These planimetric features were built as lines and converted to polygons. Census coverages from each census year were built together since they share topology. Planimetrics were created at a scale of 1:1,000. This means that a well defined feature falls within two feet of true position. When imported into the DC GIS geodatabase, the coverages shift 0.01mm since the geodatabase supports only 11 digits of precision, not double precision (16 digits). Line coverages, containing the polygon bounding attributes, accompany all polygons and are made available for editing and updating purposes. Census tracts are the only line coverages used to build polygons which carry attributes. Attribute data, kept in separate tables, was provided by US Census Bureau and the DC Office of Planning. In this case, street names were maintained at the request of the Office of Planning for ease of labeling. All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters.
441 4th St NW, Suite 930 South
Metadata imported.
Metadata imported.
Metadata imported.
Dataset copied.
Dataset copied.
Feature geometry.
ESRI
unique id
perimeter
Coverage artifact
Coverage artifact
Feature geometry.
web link url
OCTO GIS sequential identifier
Census tract number
Feature geometry.
ESRI
441 4th St NW
dcgis@dc.gov
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.
Most DC GIS datasets can be downloaded from "http://dcgis.dc.gov" on the data center page. Orders can also be made by contacting OCTO GIS at "dcgis@dc.gov", especially for datasets not available for download.
441 4th St NW, Suite 930 South