| Census Block Groups of Loudoun County, VA (2010) | |
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Data format: SDE Feature Class File or table name: GISDBB.GISBROW.CENSUS2010_BLOCKGROUPS_POLY Coordinate system: Lambert Conformal Conic Theme keywords: boundaries, boundary, Census, American Community Survey, demographic, boundaries |
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Abstract:
This GIS layer contains the geographical boundaries of the 2010 census block groups for Loudoun County, Virginia. The 2010 Census block group boundaries are used for Census Bureau statistical data tabulation purposes, including the 2010 Decennial Census and American Community Surveys.
Census block groups are part of the sub-county census geography hierarchy of tracts, block groups, and blocks. The three census geographies nest to each other, forming a hierarchy of census tract, followed by block groups, and then blocks, with blocks being the smallest. A census block group is a cluster of census blocks within the same census tract that have the same first digit of their four-digit census block numbers within a census tract. For example, block group 3 within census tract 610700 is a cluster of all the blocks numbered from 3000 to 3999 in that census tract. Block groups are uniquely numbered within census tracts, with the block group's valid range being 0 to 9.
Block Groups are designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions, census tracts and generally contain between 600 and 3,000 people or 240 and 1,200 housing units.
This 2010 Census block group GIS layer's boundaries are based on the U.S. Census Bureau Census 2010 TIGER/Line files. The boundaries are an extract of aerial photography and cartographic information, such as roads and streams, from the Loudoun County GIS system. Census block groups are bounded on all sides by visible features, such as roads, streams, lakes, power lines, and railroad tracks, and/or by non-visible boundaries such as town and county boundaries, and short line-of-sight extensions of streets and roads. |
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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.
This GIS layer contains the geographical boundaries of the 2010 census block groups for Loudoun County, Virginia. The 2010 Census block group boundaries are used for Census Bureau statistical data tabulation purposes, including the 2010 Decennial Census and American Community Surveys. Census block groups are part of the sub-county census geography hierarchy of tracts, block groups, and blocks. The three census geographies nest to each other, forming a hierarchy of census tract, followed by block groups, and then blocks, with blocks being the smallest. A census block group is a cluster of census blocks within the same census tract that have the same first digit of their four-digit census block numbers within a census tract. For example, block group 3 within census tract 610700 is a cluster of all the blocks numbered from 3000 to 3999 in that census tract. Block groups are uniquely numbered within census tracts, with the block group's valid range being 0 to 9. Block Groups are designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions, census tracts and generally contain between 600 and 3,000 people or 240 and 1,200 housing units. This 2010 Census block group GIS layer's boundaries are based on the U.S. Census Bureau Census 2010 TIGER/Line files. The boundaries are an extract of aerial photography and cartographic information, such as roads and streams, from the Loudoun County GIS system. Census block groups are bounded on all sides by visible features, such as roads, streams, lakes, power lines, and railroad tracks, and/or by non-visible boundaries such as town and county boundaries, and short line-of-sight extensions of streets and roads.
Census block groups are used in demographic analyses of Loudoun County. Census block groups are used to gain a detailed picture of population, housing, economic, and other demographic characteristics within a given area.
Loudoun County's block groups were delineated by Loudoun County Government during the Census Bureau's Participant Statistical Areas Program for the 2010 Census. The 2010 Census block layer has been modified from the Census Bureau's Tiger line file. Users should be aware that the Census's Tiger line data is devised from a mix of national and local GIS data sets. When the Tiger line data is overlaid with Loudoun County Government's detailed GIS layers it can be determined that the Census Bureau's Tiger line boundaries in some cases are slightly off from the actual location of the physical features, natural features, and governmental units such as town boundaries that they are designated to follow. The 2010 Loudoun census block group layer was generated by Loudoun County so that the block group boundaries would overlay with the features in Loudoun County's GIS data sets that the boundary are designated to follow. The 2010 Census block group boundaries are used for Census Bureau statistical data tabulation purposes, including the 2010 Decennial Census and American Community Surveys. The American Community Survey replaced the long form of the decennial Census. The American Community Survey data sets are released annually. The 2010 to 2019 American Community Survey one-year data sets, the 2008-2010 through 2018-2020 three-year data sets, and the 2006-2010 through 2016-2020 five-year data sets will all use the 2010 Census block group geographies for statistical tabulation purposes. Data are stored in the corporate ArcSDE Geodatabase as a polygon feature class. The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN (vertical datum, if applicable, NAVD88), US Survey foot units.
publication date
Every reasonable effort has been made to assure the accuracy of these data. Loudoun County, Virginia does not assume any liability arising from the use of these data. These data are provided without warranty of any kind, expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular service. Reliance on these data is at the risk of the user. These data were generated for use by Loudoun County and are available to the public. These data are intended for use at 1:2400 scale or smaller. Acknowledgement of Loudoun County would be appreciated in products derived from this data.
803 Sycolin Rd, Suite 104
MS 61
Retention of attribute accuracy throughout the personal geodatabase or shapefile to ArcSDE geodatabase feature class coversion process was ensured by a manual or automatic QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have, on a record by record basis, identical attribution when comparing all concatenated fields to all the user-defined attribution.
Topologically clean
Features may have been eliminated or generalized due to scale and intended use. To assist Loudoun County, Virginia in the maintenance of the data, please provide any information concerning discovered errors, omissions, or other discrepancies found in the data.
Retention of coordinate accuracy throughout the personal geodatabase or shapefile to ArcSDE geodatabase feature class conversion process was ensured by a manual or automatic QA/QC programmatic check. To meet satisfactory QA/QC requirements the input coverage and output feature class must have the same record total, and on a record by record basis, area, perimeter, and length differential of less than +/- 0.5%.
Demographic data source for population, housing units, and households for census block groups
Provided the foundation upon which census blocks were drawn. The 2010 Census blocks were the basis for devising the census tract boundaries.
Census block shapefile downloaded from the U.S. Census Bureau. Overlaid the Census Bureau shapefile with with Loudoun County Government's detailed GIS layers to determine the actual location of the physical features, natural features, and governmental units such as town boundaries that the census blocks are designated to follow. Digitized lines using Loudoun County Government's detailed GIS layers. Created the block group layer by spatially dissolving the census block layer.
Metadata imported.
Dataset copied.
Internal feature number.
ESRI
Feature geometry.
ESRI
Federal Information Processing State and County Code. It is a five digit code that identifies the state and county of the census block group. The first two digits designate the state and are the state FIPS code. The last three digits designate the county and are the County FIPS code
Loudoun County
the census tract that the block group is within
Loudoun County
One digit number that identifies the census block group within a census tract
Loudoun County
The federal information process codes.
Loudoun County
population of the block group
Loudoun County
housing unit count for the block group
Loudoun County
households of the block group. Households are occupied housing units
Loudoun County
Date feature class created or modified.
Loudoun County
Not for public distribution. Internal User ID of editor creating or modifying feature class.
Loudoun County
Area of census blockgroup in internal units
Loudoun County
Perimeter of census blockgroup in internal units
Loudoun County
BL_FIPSSTCO: Federal Information Processing State and County Code
51107 - Virginia (51) and Loudoun County (107)
REQUIRED:<"list proper 2-letter Prefix> FL_UPD_SOURCE: Source that created or modified feature class
0 Undetermined 1 Legacy 2 County 3 Contract
1 Harrison Street S.E., 2nd floor
MS 65
Every reasonable effort has been made to assure the accuracy of these data. Loudoun County, Virginia does not assume any liability arising from the use of these data. These data are provided without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular service. Reliance on these data is at the risk of the user.
ESRI Personal Geodatabase Feature Class
ESRI Shapefile
AutoCad Digital Exchange File
Size limit: 4.5 GB. Visit our website at: http://www.loudoun.gov/omagi, click on "Loudoun County Mapping Documents & Order Forms." The "Forms" directory will lead you to custom & standard (countywide) data order forms. Hardcopy maps may also be available; please contact the Mapping Office Public Information Counter for more information regarding all data requests.
1 Harrison Street SE, 2nd Floor
MS 65